Update hwacha opcodes

This pull request should fix issues #3 and #5.

* Update generated opcodes_hwacha_ut.h (generated from riscv-opcodes)
* Add the missing hwacha/insns_ut/ut_*.h header files. These are copies
  of the equivalent headers in riscv/insns (e.g., ut_beq.h is a copy of
  beq.h)