Memory leaks in AArch64 tests api.dis-a64 and api.ir_negative

#4117 (closed) put in better cleanup of standalone mode, including complaints about un-freed memory. The AArch64 tests were not running there despite multiple attempts so it went in with only a build test. It ends up revealing some missing cleanup in these tests:

http://139.178.83.194:8080/job/DynamoRIO-AArch64-Precommit/1078/console

<Application /var/lib/jenkins/.jenkins/workspace/DynamoRIO-AArch64-Precommit/build/build_debug-internal-64/suite/tests/bin/api.dis-a64 (6496) DynamoRIO usage error : memory leak detected>

<Application /var/lib/jenkins/.jenkins/workspace/DynamoRIO-AArch64-Precommit/build/build_debug-internal-64/suite/tests/bin/api.ir_negative (6491) DynamoRIO usage error : memory leak detected>