[AArch64] Bugfix when using execute-only and memtag sanitizer together (#133084)
Support for execute-only code generation (#125687) introduced a bug in
the case where the memtag sanitizer is used in a module containing a mix
of execute-only and non-execute-only functions.
The bug is caused by using `return` instead of `break` to short-circuit
a loop, which meant that the rest of the function dealing with memtag
sanitizer logic wasn't run.