VS: Refactor compiler id detection project file template

Make the `ClCompile` element name and `PostBuildEvent/Command` value
configurable.  Move the current content into default values for the
corresponding variables.

Modules/CMakeDetermineCompilerId.cmake

@@ -235,6 +235,8 @@ Id flags: ${testflags} ${CMAKE_${lang}_COMPILER_ID_FLAGS_ALWAYS}
     endif()
     set(id_dir ${CMAKE_${lang}_COMPILER_ID_DIR})
     set(id_src "${src}")
+    set(id_compile "ClCompile")
+    set(id_PostBuildEvent_Command "for %%i in (${id_cl}) do %40echo CMAKE_${lang}_COMPILER=%%~$PATH:i")
     configure_file(${CMAKE_ROOT}/Modules/CompilerId/VS-${v}.${ext}.in
       ${id_dir}/CompilerId${lang}.${ext} @ONLY)
     if(CMAKE_VS_MSBUILD_COMMAND AND NOT lang STREQUAL "Fortran")

Modules/CompilerId/VS-10.vcxproj.in

@@ -49,11 +49,11 @@
       <SubSystem>Console</SubSystem>
     </Link>
     <PostBuildEvent>
-      <Command>for %%i in (@id_cl@) do %40echo CMAKE_@id_lang@_COMPILER=%%~$PATH:i</Command>
+      <Command>@id_PostBuildEvent_Command@</Command>
     </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemGroup>
-    <ClCompile Include="@id_src@" />
+    <@id_compile@ Include="@id_src@" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
 </Project>