Make x86_64.rules more usable.

[dot-asm]

Until now we had to remove a bunch of bookeeping instructions to make .cl work. These new rules minimize the need for the said adjustments.

[dot-asm]

Consider suggested

#! re:(?:-?\w+)?\(%r[\w,%]+\)(.+#!.+) = %%EA\1

What I wanted is

#! re:(?:-?\w+)?\(%r[\w,%]+\)(.+#! EA.+) = %%EA\1

but it didn't work. I've traced the issue to the fact [that] the to_zsdl.py invokes instr.applySubst() twice. As in

# Translate instructions
def translate_instrs(tspec, instrs):
  # Apply variable substitutions
  substs, rules = tspec
  for instr in instrs:
    instr.applySubst()
    for lhs, rhs in substs.items():
      instr.dsl = re.sub(lhs, rhs, instr.dsl)
    instr.applySubst()
    ...

I wonder what was the rationale for the first instr.applySubst() call. The reason I ask is because it's the one that prevents the rule with (.+#! EA.+).

[dot-asm]

As for sbb bug in the additional commit. Somehow the rule is actually never invoked. The sbb with memory operand gets handled by sbb $1v, ...' somehow, I'm looking into it...