At the same time, tidy the code wrt MIPS and SH4 which have the
same two register return mechanism. Fix confusion between pipe
and pipe2 with an explicit flags=0, when the guest will not be
using the two register return mechanism.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>