STYLE: fix #7146, add documentation for

CMAKE[_SYSTEM]_(LIBRARY|PROGRAM|INCLUDE|PREFIX)_PATH variables
-moved CMAKE_CROSSCOMPILING from "Variables that modify behaviour" to
"variables that Provide Information", since it should be used only for
testing whether we are currently in cross compiling mode, not for switching
between the modes.

Alex

Source/cmDocumentVariables.cxx

@@ -78,6 +78,13 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      "useful for adding special flags and commands based"
      " on the final build environment. ", false, 
      "Variables that Provide Information");
+  cm->DefineProperty
+    ("CMAKE_CROSSCOMPILING", cmProperty::VARIABLE,
+     "Is CMake currently cross compiling.",
+     "This variable will be set to true by CMake if CMake is cross "
+     "compiling. Specifically if the build platform is different "
+     "from the target platform.", false,
+     "Variables that Provide Information");
   cm->DefineProperty
     ("CMAKE_CACHEFILE_DIR", cmProperty::VARIABLE,
      "The directory with the CMakeCache.txt file.",
@@ -417,14 +424,6 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      "CMakeLists file.",false,
      "Variables That Change Behavior");
 
-  cm->DefineProperty
-    ("CMAKE_CROSSCOMPILING", cmProperty::VARIABLE,
-     "Is CMake currently cross compiling.",
-     "This variable will be set to true by CMake if CMake is cross "
-     "compiling. Specifically if the build platform is different "
-     "from the target platform.", false,
-     "Variables That Change Behavior");
-
   cm->DefineProperty
     ("CMAKE_INSTALL_PREFIX", cmProperty::VARIABLE,
      "Install directory used by install.",
@@ -443,6 +442,97 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      false,
      "Variables That Change Behavior");
 
+  cm->DefineProperty
+    ("CMAKE_PREFIX_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_XXX(), with appropriate suffixes added.",
+     "Specifies a path which will be used by the FIND_XXX() commands. It "
+     "contains the \"base\" directories, the FIND_XXX() commands append "
+     "appropriate subdirectories to the base directories. So FIND_PROGRAM() "
+     "adds /bin to each of the directories in the path, FIND_LIBRARY() "
+     "appends /lib to each of the directories, and FIND_PATH() and "
+     "FIND_FILE() append /include . By default it is empty, it is intended "
+     "to be set by the project. See also CMAKE_SYSTEM_PREFIX_PATH, "
+     "CMAKE_INCLUDE_PATH, CMAKE_LIBRARY_PATH, CMAKE_PROGRAM_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_INCLUDE_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_FILE() and FIND_PATH().",
+     "Specifies a path which will be used both by FIND_FILE() and "
+     "FIND_PATH(). Both commands will check each of the contained directories "
+     "for the existence of the file which is currently searched. By default "
+     "it is empty, it is intended to be set by the project. See also "
+     "CMAKE_SYSTEM_INCLUDE_PATH, CMAKE_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_LIBRARY_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_LIBRARY().",
+     "Specifies a path which will be used by FIND_LIBRARY(). FIND_LIBRARY() "
+     "will check each of the contained directories for the existence of the "
+     "library which is currently searched. By default it is empty, it is "
+     "intended to be set by the project. See also CMAKE_SYSTEM_LIBRARY_PATH, "
+     "CMAKE_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_PROGRAM_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_PROGRAM().",
+     "Specifies a path which will be used by FIND_PROGRAM(). FIND_PROGRAM() "
+     "will check each of the contained directories for the existence of the "
+     "program which is currently searched. By default it is empty, it is "
+     "intended to be set by the project. See also CMAKE_SYSTEM_PROGRAM_PATH, "
+     " CMAKE_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_SYSTEM_PREFIX_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_XXX(), with appropriate suffixes added.",
+     "Specifies a path which will be used by the FIND_XXX() commands. It "
+     "contains the \"base\" directories, the FIND_XXX() commands append "
+     "appropriate subdirectories to the base directories. So FIND_PROGRAM() "
+     "adds /bin to each of the directories in the path, FIND_LIBRARY() "
+     "appends /lib to each of the directories, and FIND_PATH() and "
+     "FIND_FILE() append /include . By default this contains the standard "
+     "directories for the current system. It is NOT intended "
+     "to be modified by the project, use CMAKE_PREFIX_PATH for this. See also "
+     "CMAKE_SYSTEM_INCLUDE_PATH, CMAKE_SYSTEM_LIBRARY_PATH, "
+     "CMAKE_SYSTEM_PROGRAM_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_SYSTEM_INCLUDE_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_FILE() and FIND_PATH().",
+     "Specifies a path which will be used both by FIND_FILE() and "
+     "FIND_PATH(). Both commands will check each of the contained directories "
+     "for the existence of the file which is currently searched. By default "
+     "it contains the standard directories for the current system. It is "
+     "NOT intended to be modified by the project, use CMAKE_INCLUDE_PATH "
+     "for this. See also CMAKE_SYSTEM_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_SYSTEM_LIBRARY_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_LIBRARY().",
+     "Specifies a path which will be used by FIND_LIBRARY(). FIND_LIBRARY() "
+     "will check each of the contained directories for the existence of the "
+     "library which is currently searched. By default it contains the "
+     "standard directories for the current system. It is NOT intended to be "
+     "modified by the project, use CMAKE_SYSTEM_LIBRARY_PATH for this. See "
+     "also CMAKE_SYSTEM_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
+    ("CMAKE_SYSTEM_PROGRAM_PATH", cmProperty::VARIABLE,
+     "Path used for searching by FIND_PROGRAM().",
+     "Specifies a path which will be used by FIND_PROGRAM(). FIND_PROGRAM() "
+     "will check each of the contained directories for the existence of the "
+     "program which is currently searched. By default it contains the "
+     "standard directories for the current system. It is NOT intended to be "
+     "modified by the project, use CMAKE_PROGRAM_PATH for this. See also "
+     "CMAKE_SYSTEM_PREFIX_PATH.", false,
+     "Variables That Change Behavior");
+
   cm->DefineProperty
     ("CMAKE_USER_MAKE_RULES_OVERRIDE", cmProperty::VARIABLE,
      "Specify a file that can change the build rule variables.",