Revert "libc: Use the fast strlen on Scorpion too"

This reverts commit 9da0db97dd4960ca6e0fbb0e6e96179bda43f3fb.
Revert "Bionic: Add AOSP master cortex optimizations"

This reverts commit 456c0e8cbe4ed2da25317e8e46ed327a14fbeb1c.