[asan-asm-instrumentation] CFI directives are generated for .S files.

Summary: CFI directives are generated for .S files.

Reviewers: eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5520

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219199 91177308-0d34-0410-b5e6-96231b3b80d8