MIPS64: Implement intrinsics from libcore.io.Memory:

- peekByte(long address)
- peekShort(long address)
- peekInt(long address)
- peekLong(long address)
- pokeByte(long address, byte value)
- pokeShort(long address, short value)
- pokeInt(long address, int value)
- pokeLong(long address, long value)

Change-Id: Ic5996ea035bf7e622b6fc85b9526ee8318cb6b1f