AArch64 is missing XINST_CREATE and INSTR_CREATE macros

Split from #1569. AArch64 is missing a number of XINST_CREATE macros, and nearly all of its INSTR_CREATE macros. This is hindering tool development: e.g., I'm adding some instrumentation to drcachesim that does an AND operation yet there's no XINST_CREATE_and_s. This makes it difficult for new tool code to be cross-platform. It would be best to avoid new code having to be disabled for AArch64.