Teach the CheckCompilerRelatedVariables test to verify MSVC11. Update
the special cases already in the Preprocess and VSExternalInclude tests
for VS 10 to work for VS 11 too.
Some HPUX compilers give this error: Error 690: "/home/cport/Dashboards/My Tests/CMake-build/Tests/CheckCompilerRelatedVariables/main.cxx", line 1 # Nonempty source files must end with a newline that is not preceded by a backslash.