tcg: Relax requirement for mulu2_i32 on 32-bit hosts

Instead require either mulu2_i32 or muluh_i32.  The code in tcg-op.h
already supports looking for both.  Previous incomplete conversion?

Signed-off-by: Richard Henderson <rth@twiddle.net>
tcg: Use tcg_gen_mulu2_i32 in tcg_gen_muls2_i32

Rather than hard-coding use of mulu2_i32, allow muluh_i32.

Signed-off-by: Richard Henderson <rth@twiddle.net>
tcg: Fix fallback from muls2_i64 to mulu2_i64

Brown Bag sez, don't put the fallback code into the wrong function.
Also, check for muluh_i64 and use tcg_gen_mulu2_i64 instead of raw ops.

Signed-off-by: Richard Henderson <rth@twiddle.net>