i#1569 AArch64: Add missing "flags" argument in call to SYS_unlinkat.
i#1569 AArch64: Add missing "flags" argument in call to SYS_unlinkat.

This old bug explains why 97abbd4 broke client.drx-test on AArch64.

Review-URL: https://codereview.appspot.com/309590043

AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio