Add header files to CMake build solution. It use globing so it doesn't need to be...

Add header files to CMake build solution. It use globing so it doesn't need to be manually maintained, but it won't automatically detect a new header. I think this is a good compromise for the header files, since there presence in the solution is just an help for the user. Moreover, a new header is often introduced with a new cpp source file which need a makefile change, which will regenerate the solution and detect the new header.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58566 91177308-0d34-0410-b5e6-96231b3b80d8