Fix MacOSX since "imported" and "Imported::imported" are ambiguous. Test that...

Fix MacOSX since "imported" and "Imported::imported" are ambiguous. Test that we can read the global when specified with the global namespace and test that we can read "Imported::imported" correctly. The commented out test should be testing for ambiguity when just "imported" is evaluated as an expression, but that doesn't work yet.

llvm-svn: 247764