[sledge] Remove `.<int>` suffix when looking up modeled function names
[sledge] Remove `.<int>` suffix when looking up modeled function names

Summary:
It seems that functions internalized by llvm no longer have valid
mangled names, and instead have a `.<int>` suffix. This diff removes
these unpredictable suffixes when checking if a called function is a
specified/modeled intrinsic.

Reviewed By: kren1

Differential Revision: D16059781

fbshipit-source-id: a4b9f6c73

facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer