Set -fomit-frame-pointer for all devices

-fomit-frame-pointer was only being set for arm and mips.  Since
we always use unwind tables and not frame pointers to unwind, and
since ART generated code does not use frame pointers, just turn
off frame pointers everywhere to gain an extra register.

Bug: 68951394
Test: m checkbuild
Change-Id: I9237d486a0c0215cdafd96d66712082df0eba785