Disable pre-gc-heap-verification in debug builds

There is enough evidence that the memory corruption bugs are manifesting
during the GC. So verifying the heap before GC won't help in identifying
any bugs. On the other hand, it adds enough overhead to cause some
tests' timeout.

Test: art/test/testrunner/testrunner.py --host --debug
Change-Id: Ia6480097c3259255e1ca6a6a885a16928b39e453
1 file changed