libavutil/ppc/util_altivec.h : fix unaligned_load() vec_unaligned_load() add macros VEC_LD() VEC_MERGEH() VEC_MERGEL() VEC_ST() for POWER LE

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
libavcodec/ppc/hpeldsp_altivec.c : fix ff_put_pixels16_altivec() put_no_rnd_pixels16_xy2_altivec() put_no_rnd_pixels8_xy2_altivec() avg_pixels8_altivec() avg_pixels8_xy2_altivec() put_pixels16_xy2_altivec() put_pixels8_xy2_altivec() ff_avg_pixels16_altivec() for POWER LE

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>