Auditor should also look at the registers used by the instructions

[giordano]

In #832 there is a test where the auditor misidentifies a haswell object file as sandybridge, because it uses an AVX instruction, but with ymm register, which causes a SIGILL when running it on a sandybridge machine:

$ ./main 256; dmesg | last -n 1
[3577511.181215] traps: main[528] trap invalid opcode ip:401108 sp:7ffdb1d9ca00 error:0 in main[401000+1000]
$ objdump -d main | grep 401108
  401108:       c5 f5 fe ca             vpaddd %ymm2,%ymm1,%ymm1

A more refined way to detect the ISA would take into account also the registers used by the instructions