Reapply "[clang][cli] Report result of ParseLangArgs"

This reverts commit 6039f821 and reapplies bff6d9bb.

Clang's Index/implicit-attrs.m test invokes c-index-test with -fobjc-arc. This flag is not compatible with -fobjc-runtime=gcc, which gets implied on Linux.

The original commit uncovered this by correctly reporting issues when parsing -cc1 command line.

This commit fixes the test to explicitly provide ObjectiveC runtime compatible with ARC.