Revert "build: -fno-tree-vectorize for -mfpu=neon"

On toro, this results in lowmemkiller being a bitch.

This reverts commit 5f17696526ca3f48bec47fe1b1f9a742340fede6.

Change-Id: Ia84894dd0e09327db6814c366c472f8beab2100b