[sanitizer] support toolchains that don't understand CFI directives

Summary: Support toolchains that don't understand CFI directives.

Reviewers: dvyukov

Reviewed By: dvyukov

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2336

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@196480 91177308-0d34-0410-b5e6-96231b3b80d8