[compiler-rt] Fix Asan imports/exports unittest

Summary:
Avoid mismatch between imports/exports for 32-bit and 64-bits version.

The test is running grep over macros to detect which functions are
intercepted. Unfortunately, exception handlers differ in 32-bit and
64-bit.

This patch is removing the exception handlers from the test.

Reviewers: rnk

Subscribers: llvm-commits, wang0109, kubabrecka, chrisha

Differential Revision: https://reviews.llvm.org/D22484

llvm-svn: 275982