[XRay] Fix the test func-id-utils.cc on PPC.

Summary:
The test fails on PPC, because the address of a function may vary
depending on whether the "taker" shares the same ToC (roughly, in the
same "module") as the function.

Therefore the addresses of the functions taken in func-id-utils.cc may be
different from the addresses taken in xray runtime.

Change the test to be permissive on address comparison.

Reviewers: dberris, echristo

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33026

llvm-svn: 302686