Kill unused ARCH_* defines.

No one's using ARCH_AARCH64 or AARCH_MIPS64 yet, and ARCH_PPC was always more
aspirational than real.

Change-Id: I07c6cbad6eb0917c4c24848a98c3bc9a3fe72db6
Merge "Kill unused ARCH_* defines."
Remove another unused definition.

We have a lot of definitions around the tree, of which this is but one,
but we have no users.

Change-Id: Ic411505a0370be2b56150275fa9b8f5329241ce8
Merge "Remove another unused definition."
core: Use WITH_DEXPREOPT_PIC=true to have dex2oat build pic oat files

When WITH_DEXPREOPT=true is set, if we also set WITH_DEXPREOPT_PIC=true
then the build will generate position-independent OAT images.

This means that all the system applications no longer need to be
relocated into /data/dalvik-cache and this can achieve saving disk space
at the cost of slightly slower running code.

Bug: 18035729

(cherry picked from commit da9f1a7e82b7e6d0677553f211835625078347f2)

Change-Id: Ifd517c842f48bf31568bf5ff56667298d422c2c0
Merge "core: Use WITH_DEXPREOPT_PIC=true to have dex2oat build pic oat files"