VS: Add more placeholders to compiler id detection project file template

Modules/CMakeDetermineCompilerId.cmake

@@ -237,6 +237,10 @@ Id flags: ${testflags} ${CMAKE_${lang}_COMPILER_ID_FLAGS_ALWAYS}
     set(id_src "${src}")
     set(id_compile "ClCompile")
     set(id_PostBuildEvent_Command "for %%i in (${id_cl}) do %40echo CMAKE_${lang}_COMPILER=%%~$PATH:i")
+    set(id_Import_props "")
+    set(id_Import_targets "")
+    set(id_ItemDefinitionGroup_entry "")
+    set(id_Link_AdditionalDependencies "")
     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

@@ -25,6 +25,9 @@
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+    @id_Import_props@
+  </ImportGroup>
   <PropertyGroup>
     <_ProjectFileVersion>10.0.30319.1</_ProjectFileVersion>
     <OutDir Condition="'$(Configuration)|$(Platform)'=='Debug|@id_platform@'">.\</OutDir>
@@ -44,9 +47,11 @@
       <DebugInformationFormat>
       </DebugInformationFormat>
     </ClCompile>
+    @id_ItemDefinitionGroup_entry@
     <Link>
       <GenerateDebugInformation>false</GenerateDebugInformation>
       <SubSystem>Console</SubSystem>
+      @id_Link_AdditionalDependencies@
     </Link>
     <PostBuildEvent>
       <Command>@id_PostBuildEvent_Command@</Command>
@@ -56,4 +61,7 @@
     <@id_compile@ Include="@id_src@" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+    @id_Import_targets@
+  </ImportGroup>
 </Project>