Tests/Preprocess: Remove unnecessary VS version tests

Since commit v2.8.12~436^2 (VS 10: Escape ; as %3B in preprocessor
definitions, 2013-04-11) the Tests/Preprocessor/CMakeLists.txt file no
longer uses the PP_VS1XX values, so stop setting them.

Tests/Preprocess/CMakeLists.txt

@@ -34,15 +34,6 @@ endif()
 if("${CMAKE_GENERATOR}" MATCHES "Visual Studio")
   set(PP_VS 1)
 endif()
-if("${CMAKE_GENERATOR}" MATCHES "Visual Studio 10")
-  set(PP_VS100 1)
-endif()
-if("${CMAKE_GENERATOR}" MATCHES "Visual Studio 11")
-  set(PP_VS110 1)
-endif()
-if("${CMAKE_GENERATOR}" MATCHES "Visual Studio 12")
-  set(PP_VS120 1)
-endif()
 
 # Some tests below check the PP_* variables set above.  They are meant
 # to test the case that the build tool is at fault.  Other tests below