mat3x4: fix multiplication functions #281

Job	Run time
build_emsdk (Release)	45s
build_emsdk (Release, -msimd128)	46s
build_emsdk (Release, -msse -msse2 -msimd128)	48s
build_emsdk (Release, -msse -msse2 -msse3 -msse4 -msimd128)	45s
build_emsdk (Debug)	51s
build_emsdk (Debug, -msimd128)	54s
build_emsdk (Debug, -msse -msse2 -msimd128)	50s
build_wasi_sdk (Release, 19)	25s
build_emsdk (Debug, -msse -msse2 -msse3 -msse4 -msimd128)	52s
build_emsdk (RelWithDebInfo)	47s
build_wasi_sdk (Release, 20)	24s
build_emsdk (RelWithDebInfo, -msimd128)	46s
build_wasi_sdk (Release, -msimd128, 19)	30s
build_emsdk (RelWithDebInfo, -msse -msse2 -msimd128)	47s
build_wasi_sdk (Release, -msimd128, 20)	29s
build_emsdk (RelWithDebInfo, -msse -msse2 -msse3 -msse4 -msimd128)	52s
build_wasi_sdk (Debug, 19)	23s
build_emsdk (MinSizeRel)	48s
build_wasi_sdk (Debug, 20)	24s
build_emsdk (MinSizeRel, -msimd128)	43s
build_wasi_sdk (Debug, -msimd128, 19)	27s
build_emsdk (MinSizeRel, -msse -msse2 -msimd128)	45s
build_wasi_sdk (Debug, -msimd128, 20)	32s
build_emsdk (MinSizeRel, -msse -msse2 -msse3 -msse4 -msimd128)	50s
build_wasi_sdk (RelWithDebInfo, 19)	30s
build_wasi_sdk (RelWithDebInfo, 20)	29s
build_wasi_sdk (RelWithDebInfo, -msimd128, 19)	32s
build_wasi_sdk (RelWithDebInfo, -msimd128, 20)	35s
build_wasi_sdk (MinSizeRel, 19)	27s
build_wasi_sdk (MinSizeRel, 20)	25s
build_wasi_sdk (MinSizeRel, -msimd128, 19)	31s
build_wasi_sdk (MinSizeRel, -msimd128, 20)	28s
	20m 20s

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