AltiVec code is broken on powerpc:
motion_comp_altivec.c:48:12: warning: implicit declaration of function 'vec_ld' is invalid in C99 [-Wimplicit-function-declaration]
return vec_ld (A, (uint8_t *)B);
^
motion_comp_altivec.c:48:34: warning: cast from 'const unsigned char *' to 'unsigned char *' drops const qualifier [-Wcast-qual]
return vec_ld (A, (uint8_t *)B);
^
motion_comp_altivec.c:48:12: error: returning 'int' from a function with incompatible result type 'vector_u8_t' (vector of 16 'unsigned char' values)
return vec_ld (A, (uint8_t *)B);