Move JIT lock below kTaggingLockLevel.

JVMTI will use a lock at level kTaggingLockLevel after acquiring the JIT
lock for visiting the heap.

Also make the 913-heaps ignore system classes, which will be visited if
one of their method is being JIT compiled.

Test: 913-heaps
Change-Id: I0f2dfb829745634e0fb808d33019399cfa8ae72b
2 files changed