[DebugInfo][dsymutil] Keep locations for function-local globals

In debug info, we expect variables to have location info if they are used and we don't want location info for functions that are not used. However, if an unused function is inlined, we could have the scenario where a function is not in the final binary but its static variable is in the final binary. Ensure that variables in the final binary have location debug info even if their scope was inlined.

Also add `--implicit-check-not` to a test for clarity.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D115565