Have clang_getSpellingLocation() use the same logic as DiagnosticRenderer for...

Have clang_getSpellingLocation() use the same logic as DiagnosticRenderer for plowing through macros.

This fixes a subtle bug reported in <rdar://problem/12584554> where a double-nested
macro could lead to an incorrect fixit location with live issues.

This fix also uncovers a bunch of subtle bugs in our indexer test cases which
are now fixed (mostly around source ranges for attributes).

llvm-svn: 170468