Implement getMaxNumStubs() for x86 and x86_64.

Change-Id: I5e7a446d17d3bdf4e93fd8fdaf8fd3ef9c3de571
Signed-off-by: Xiaofei Wan <xiaofei.wan@intel.com>
Merge "Implement getMaxNumStubs() for x86 and x86_64."
Fix wrong machine identifier for AArch64 in linkloader.

This doesn't change functionality at all, since the only "machine" variant
with special handling is EM_MIPS. Thus, reconfiguring as EM_AARCH64 instead
of EM_ARM is safe (and correct).

Change-Id: I6249682155957d20253ae48d2564e5b31cf21351
Merge "Fix wrong machine identifier for AArch64 in linkloader."