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

libutils/Android.bp

@@ -182,6 +182,10 @@ cc_library {
     min_sdk_version: "apex_inherit",
 
     afdo: true,
+
+    header_abi_checker: {
+        diff_flags: ["-allow-adding-removing-weak-symbols"],
+    },
 }
 
 cc_library {