x86: templatize INC/DEC

With the multitude of new APX templates, it finally becomes desirable to
further remove redundancy by also templatizing basic arithmetic insns.
Start with the simplest case, accompanied by a necessary adjustment to
i386-gen (such that template uses can also be at the start of a line).

While there also drop a bogus (meaningless / unreachable) "break" as
well as a unused variable (which I'm surprised compilers didn't warn
about).
3 files changed