Revert "Use MAP_FIXED in remapNewHeap"

This reverts commit 798643be51d789aec8f7ad6c7dfb1ee01774babb.

Change-Id: I07a2ac84028b8b9c14f69a9452e83560b22933b8
Merge "Revert "Use MAP_FIXED in remapNewHeap"" into kitkat