rL365634 adds a unique_ptr<CompilationDatabase> in...

rL365634 adds a unique_ptr<CompilationDatabase> in GobalCompilationDatabase.h:108 but CompilationDatabase is only forward declared. This makes the header not compile standalone, because unique_ptrs expect to have the full-definition of the...

Summary:
...template argument.

Remove the forward declaration and include the appropriate header instead.
Remove CompileCommand too, which is also in the header.

llvm-svn: 365713