libc/arm: add cortex-a8 cpu variant

Change-Id: I30e8dd6d4b2e7889aea8f5ed21182a5941bfb489
libc: Replaced O(n^2) strstr with O(n)

Took it from glibc.

Change-Id: Ide8866a8db81c3df99ebae65a0c35fe1a34679ce