Optimisation of Find target

Basic info

• Fixed point:
  • Encoder (fixed): 96ae0d1c

Bug description

the computation of the impulse response inside find_target is unnecessary complex. Using W_msu_32_16(a, L_shl(c,x), b) instead of W_msu_16_16(a, b, extract_h(L_shl(c,x)), remove unnecessary operation and improve accuracy

|------------|---before--|---after---| | WMOPS Max. | 3.8 wmops | 3.4 wmops |

Ways to reproduce

-stereo -dtx 24400 48 ..\ivas-codec\scripts\testv\stvST48n.wav bit_test