target-mips: fix multiplication in mipsdsp_rndq15_mul_q15_q15
Multiplication of Q15 fractional halfword vectors was incorrect in the
previous implementation of mipsdsp_rndq15_mul_q15_q15. It failed to take
element signs into account. This change fixes it, and it adds a test case
for it.
The change also removes unnecessary cast in the function
mipsdsp_mul_q15_q15_overflowflag21().
Signed-off-by: Petar Jovanovic <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Signed-off-by: Aurelien Jarno <[email protected]>