Adding test to cover the correct import of SourceLocation pertaining to a...

Adding test to cover the correct import of SourceLocation pertaining to a built-in during expression parsing

Summary: This tests a fix in the ASTImpoter.cpp to ensure that we import built-in correctly,
see differential: https://reviews.llvm.org/D58743
Once this change is merged this test should pass and should catch regressions in this feature.

Differential Revision: https://reviews.llvm.org/D58790

llvm-svn: 355525