Revert "Revert "Revert "CLANG: Workaround for violations on unsupported command -mtune=cortex-a15"""

This reverts commit a071d1b33e6b7aa57e189e359c50f4de3ad1fe13.

Revert "Wildcardify mtune fix"

This reverts commit 74178e469d3311881abdfbe23340d2f190f252fa.

Revert "Don't krait2 all non-prebuilt-clang devices"

This reverts commit 4d4d04530324a486d9667e00c8ccf6b7b57ba455

Change-Id: I943ad10bd2a8383b95a8fc96e33cf314753cc18c