libdmabufheap: Do not create heap mappings without ION support am: 0f2cc9e07e am: aa53e0e29a am: a26f11fccf

Original change: https://android-review.googlesource.com/c/platform/system/memory/libdmabufheap/+/1792810

Change-Id: Ia80e10733d5a973a9a1d4f9c5c790fa5535fed98
tree: f71e233c230fb661f6af0aa5c05e6760a7f243fb
  1. include/
  2. tests/
  3. Android.bp
  4. BufferAllocator.cpp
  5. BufferAllocatorWrapper.cpp