fix a crasher when running out of memory

MemoryHeapBase::getBase() returns MAP_FAILED in case or
OOM, not null which is what SF was checking against.

This addresses one of the issues of bug 7230543.

Bug: 7230543
Change-Id: I763a88f64a2f9ff75eb139cfbaf9a1a9746c5577
2 files changed