FindSDL: Use prefix SDL_NET, because it matches the file name.

Add new variables, keep the old ones for compatibility.
Format the documentation header.

Modules/FindSDL_net.cmake

@@ -1,9 +1,14 @@
-# Locate SDL_net library
-# This module defines
-# SDLNET_LIBRARY, the name of the library to link against
-# SDLNET_FOUND, if false, do not try to link against
-# SDLNET_INCLUDE_DIR, where to find the headers
-# SDLNET_VERSION_STRING - human-readable string containing the version of SDL_net
+# - Locate SDL_net library
+# This module defines:
+#  SDL_NET_LIBRARIES, the name of the library to link against
+#  SDL_NET_INCLUDE_DIRS, where to find the headers
+#  SDL_NET_FOUND, if false, do not try to link against
+#  SDL_NET_VERSION_STRING - human-readable string containing the version of SDL_net
+#
+# For backward compatiblity the following variables are also set:
+#  SDLNET_LIBRARY (same value as SDL_NET_LIBRARIES)
+#  SDLNET_INCLUDE_DIR (same value as SDL_NET_INCLUDE_DIRS)
+#  SDLNET_FOUND (same value as SDL_NET_FOUND)
 #
 # $SDLDIR is an environment variable that would
 # correspond to the ./configure --prefix=$SDLDIR
@@ -26,7 +31,7 @@
 # (To distribute this file outside of CMake, substitute the full
 #  License text for the above reference.)
 
-find_path(SDLNET_INCLUDE_DIR SDL_net.h
+find_path(SDL_NET_INCLUDE_DIR SDL_net.h
   HINTS
     ENV SDLNETDIR
     ENV SDLDIR
@@ -43,7 +48,7 @@ find_path(SDLNET_INCLUDE_DIR SDL_net.h
   /opt/csw # Blastwave
   /opt
 )
-find_library(SDLNET_LIBRARY
+find_library(SDL_NET_LIBRARY
   NAMES SDL_net
   HINTS
     ENV SDLNETDIR
@@ -58,24 +63,34 @@ find_library(SDLNET_LIBRARY
   /opt
 )
 
-if(SDLNET_INCLUDE_DIR AND EXISTS "${SDLNET_INCLUDE_DIR}/SDL_net.h")
-  file(STRINGS "${SDLNET_INCLUDE_DIR}/SDL_net.h" SDLNET_VERSION_MAJOR_LINE REGEX "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+[0-9]+$")
-  file(STRINGS "${SDLNET_INCLUDE_DIR}/SDL_net.h" SDLNET_VERSION_MINOR_LINE REGEX "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+[0-9]+$")
-  file(STRINGS "${SDLNET_INCLUDE_DIR}/SDL_net.h" SDLNET_VERSION_PATCH_LINE REGEX "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+[0-9]+$")
-  string(REGEX REPLACE "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+([0-9]+)$" "\\1" SDLNET_VERSION_MAJOR "${SDLNET_VERSION_MAJOR_LINE}")
-  string(REGEX REPLACE "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+([0-9]+)$" "\\1" SDLNET_VERSION_MINOR "${SDLNET_VERSION_MINOR_LINE}")
-  string(REGEX REPLACE "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+([0-9]+)$" "\\1" SDLNET_VERSION_PATCH "${SDLNET_VERSION_PATCH_LINE}")
-  set(SDLNET_VERSION_STRING ${SDLNET_VERSION_MAJOR}.${SDLNET_VERSION_MINOR}.${SDLNET_VERSION_PATCH})
-  unset(SDLNET_VERSION_MAJOR_LINE)
-  unset(SDLNET_VERSION_MINOR_LINE)
-  unset(SDLNET_VERSION_PATCH_LINE)
-  unset(SDLNET_VERSION_MAJOR)
-  unset(SDLNET_VERSION_MINOR)
-  unset(SDLNET_VERSION_PATCH)
+if(SDL_NET_INCLUDE_DIR AND EXISTS "${SDL_NET_INCLUDE_DIR}/SDL_net.h")
+  file(STRINGS "${SDL_NET_INCLUDE_DIR}/SDL_net.h" SDL_NET_VERSION_MAJOR_LINE REGEX "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+[0-9]+$")
+  file(STRINGS "${SDL_NET_INCLUDE_DIR}/SDL_net.h" SDL_NET_VERSION_MINOR_LINE REGEX "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+[0-9]+$")
+  file(STRINGS "${SDL_NET_INCLUDE_DIR}/SDL_net.h" SDL_NET_VERSION_PATCH_LINE REGEX "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+[0-9]+$")
+  string(REGEX REPLACE "^#define[ \t]+SDL_NET_MAJOR_VERSION[ \t]+([0-9]+)$" "\\1" SDL_NET_VERSION_MAJOR "${SDL_NET_VERSION_MAJOR_LINE}")
+  string(REGEX REPLACE "^#define[ \t]+SDL_NET_MINOR_VERSION[ \t]+([0-9]+)$" "\\1" SDL_NET_VERSION_MINOR "${SDL_NET_VERSION_MINOR_LINE}")
+  string(REGEX REPLACE "^#define[ \t]+SDL_NET_PATCHLEVEL[ \t]+([0-9]+)$" "\\1" SDL_NET_VERSION_PATCH "${SDL_NET_VERSION_PATCH_LINE}")
+  set(SDL_NET_VERSION_STRING ${SDL_NET_VERSION_MAJOR}.${SDL_NET_VERSION_MINOR}.${SDL_NET_VERSION_PATCH})
+  unset(SDL_NET_VERSION_MAJOR_LINE)
+  unset(SDL_NET_VERSION_MINOR_LINE)
+  unset(SDL_NET_VERSION_PATCH_LINE)
+  unset(SDL_NET_VERSION_MAJOR)
+  unset(SDL_NET_VERSION_MINOR)
+  unset(SDL_NET_VERSION_PATCH)
 endif()
 
+set(SDL_NET_LIBRARIES ${SDL_NET_LIBRARY})
+set(SDL_NET_INCLUDE_DIRS ${SDL_NET_INCLUDE_DIR})
+
 include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
 
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDLNET
-                                  REQUIRED_VARS SDLNET_LIBRARY SDLNET_INCLUDE_DIR
-                                  VERSION_VAR SDLNET_VERSION_STRING)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL_net
+                                  REQUIRED_VARS SDL_NET_LIBRARIES SDL_NET_INCLUDE_DIRS
+                                  VERSION_VAR SDL_NET_VERSION_STRING)
+
+# for backward compatiblity
+set(SDLNET_LIBRARY ${SDL_NET_LIBRARIES})
+set(SDLNET_INCLUDE_DIR ${SDL_NET_INCLUDE_DIRS})
+set(SDLNET_FOUND ${SDL_NET_FOUND})
+
+mark_as_advanced(SDL_NET_LIBRARY SDL_NET_INCLUDE_DIR)