Add lldb data formatters for clang classes, starting with SourceLocation.

When installed, instead of getting this:

(lldb) p Tok.Loc
(clang::SourceLocation) $0 = {
  (unsigned int) ID = 123582
}

you'll get:

(lldb) p Tok.Loc
(clang::SourceLocation) $4 = "/usr/include/i386/_types.h:37:1" (offset: 123582, file)

This depends on r167629.

llvm-svn: 167640