[GWP-ASan] Use functions in backtrace test, not line numbers.

Summary:
There's no unwinding functionality on Android that allows for line
numbers to be retrieved in-process. As a result, we can't have
this backtrace test run on Android.

Cleanup the test to use optnone functions instead, which is more stable
than line numbers anyway.

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: #sanitizers, morehouse, cferris

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D76807

Bug: 152414185
Test: atest gwp_asan_unittest

GitOrigin-RevId: 1216f4c0ea0c232d545ce3ab8f858c696e085d47
Change-Id: I298b8753e78c5a656d60d70415c5c1603918047c
1 file changed