Help: Refactor PDB_NAME and PDB_OUTPUT_DIRECTORY docs

Move the note about VS 6 into the PDB_NOTE.txt common include file
and include it from the per-config properties too.  Also re-word
the note to clarify the separate compiler and linker flags involved
and state explicitly that compiler flags are not affected.

Help/prop_tgt/PDB_NAME.rst

@@ -8,6 +8,3 @@ This property specifies the base name for the debug symbols file.
 If not set, the logical target name is used by default.
 
 .. include:: PDB_NOTE.txt
-
-This property is not implemented by the :generator:`Visual Studio 6`
-generator.

Help/prop_tgt/PDB_NAME_CONFIG.rst

@@ -6,5 +6,4 @@ generated by the linker for an executable or shared library target.
 
 This is the configuration-specific version of :prop_tgt:`PDB_NAME`.
 
-This property is not implemented by the :generator:`Visual Studio 6`
-generator.
+.. include:: PDB_NOTE.txt

Help/prop_tgt/PDB_NOTE.txt

@@ -3,6 +3,10 @@
  is invoked to produce them so they have no linker-generated ``.pdb`` file
  containing debug symbols.
 
- The compiler-generated program database files specified by the MSVC
- ``/Fd`` flag are not the same as linker-generated program database
- files and so are not influenced by this property.
+ The linker-generated program database files are specified by the
+ ``/pdb`` linker flag and are not the same as compiler-generated
+ program database files specified by the ``/Fd`` compiler flag.
+ This property does not influence the latter.
+
+ This property is not implemented by the :generator:`Visual Studio 6`
+ generator.

Help/prop_tgt/PDB_OUTPUT_DIRECTORY.rst

@@ -10,6 +10,3 @@ value of the :variable:`CMAKE_PDB_OUTPUT_DIRECTORY` variable if it is
 set when a target is created.
 
 .. include:: PDB_NOTE.txt
-
-This property is not implemented by the :generator:`Visual Studio 6`
-generator.

Help/prop_tgt/PDB_OUTPUT_DIRECTORY_CONFIG.rst

@@ -11,5 +11,4 @@ property is initialized by the value of the
 :variable:`CMAKE_PDB_OUTPUT_DIRECTORY_<CONFIG>` variable if it is
 set when a target is created.
 
-This property is not implemented by the :generator:`Visual Studio 6`
-generator.
+.. include:: PDB_NOTE.txt