RESTRICT AUTOMERGE Ignore weak symbol difference in libutils ABI check

The diff_flags make the ABI checker ignore the weak symbol difference
caused by PGO.

Ignore-AOSP-First: This patch relaxes the ABI check for T only.
                   b/232982219 tracks the long-term solution.
Test: make libutils.vendor
Bug: 230076879
Change-Id: I8ec2c0f5a540263b4e8a0a4f9cf26f9c297593b5