Fix mips64 build

Added missing register definitions in header.S for mips64.
We needed this because machine/regdef.h has been removed from
bionic.
Generated mterp_mips64.S using gen-mterp.py script.

Test: successful mips64 build

Change-Id: I6a2f4fcf8a827f6198f3c97f3a3dd35b7bc79c7e