Zero: DO_UPDATE_INSTRUCTION_COUNT should only update when relevant VM flags are set

Everywhere else in VM code we effectively do:

  if (CountBytecodes || TraceBytecodes || StopInterpreterAt) BytecodeCounter::...
  if (PrintBytecodeHistogram) BytecodeHistogram::...

But not in DO_UPDATE_INSTRUCTION_COUNT macro.

Adding these flags avoid the writes to statistics what would never be used (and those writes can even contend, afaics).

This change drops the Linux x86_64 Zero fastdebug build time from ~18m to ~17.5m.