ART: Relax java_vm_ext test

Bionic gives more than the requested stack size in some cases, see
change-id I7037ac8273ebe54dd19b1561c7a376819049124c. In that case,
attaching a thread with STACK_MIN may actually succeed.

Bug: 18908062
Change-Id: Ibb3f5c7a7399c01ec2032a133896cf91327370ed
1 file changed