Attempt to read load_base from memory when needed.

When creating the map list, always try and read the load base
using the memory functions for local unwinds. For remote unwinds,
if we can't map in the elf image, then try and use the memory
functions instead.

Bug: 21381155
Change-Id: I28d0dbed585bbcd366a01d9313b463745059d737
11 files changed