[GWP-ASan] Scan GWP-ASan regions for native allocations.

GWP-ASan is part of the native allocator, and may allocate some memory.
When GWP-ASan is enabled, JNI needs to look inside of
GWP-ASan regions as well for native allocations.

Bug: 135634846
Test: ???
Change-Id: Id4f15544a902a034687690214c9481ab963929fc