[compiler-rt] Add -fno-omit-frame-pointer check to builtins

rG210d72e9d6b4a8e7633921d0bd7186fd3c7a2c8c moved the check from
builtin-config-ix to config-ix so that the check would be made even when
the builtins are not built. However, now the check is no longer made
when the builtins are built standalone which causes the builtins to fail
to build.

Add the check back to builtins-config-ix so that the check gets
performed both when the builtins are not built, and when they are built
standalone.

Reviewed By: smeenai

Differential Revision: https://reviews.llvm.org/D110879