Revert "arm: remove "optimized" SHA1 routines"

This reverts commit f74a374a348d2192a8e787af7d954dc29ee4cd2c.
Revert "lib/sha1: use the git implementation of SHA-1"

This reverts commit 6b68c9bd677c3cc735f9c60d9e5be9947487ed67.
customize pegasusq