[cond-optab] Convert m32c

[Paolo Bonzini]

DJ Delorie wrote:
> This is OK with me.

Thanks.

By the way, this patch survived full comparison of assembly output from
the testsuite (-mcpu={r8c,m16c,m32c}) with minor improvements on
base-gcc-src/gcc/testsuite/gcc.c-torture/execute/divconst-2.c (and a few
other tests at -O0 only), and no change otherwise.  The changes were
small enough that I could look at each of them.

Paolo