[LLVM-C] Add Accessors For Global Variable Metadata Properties
Summary: Metadata for a global variable is really a (GlobalVariable, Expression) tuple. Allow access to these, then allow retrieving the file, scope, and line for a DIVariable, whether global or local. This should be the last of the accessors required for uniform access to location and file information metadata.
Reviewers: jberdine, whitequark, deadalnix
Reviewed By: jberdine, whitequark
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D60725