Merge "Move Half implementations to libcore to allow ART optimizations" am: 6bf381b5b1 am: eaad9ac3e2 am: 62a0694411 am: 0e3a540d18
am: 2cc8b8a8e9

Change-Id: If89cc2e62827e521fb501fc6f7e73e12f8da37ee