Debug info: Let dbg.values inserted by LowerDbgDeclare inherit the location
of the dbg.value. This gets rid of tons of redundant variable DIEs in
subscopes.

rdar://problem/14874886, rdar://problem/16679936

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207135 91177308-0d34-0410-b5e6-96231b3b80d8