Fixup for r220403: Use getFileLoc() instead of getSpellingLoc() in SanitizerBlacklist.

This also handles the case where function name (not its body)
is obtained from macro expansion.
DebugInfo: Omit scopes in -gmlt to reduce metadata size (on disk and in memory)

I haven't done any actual impact analysis of this change as it's a
strict improvement, but I'd be curious to know how much it helps.