vp9: enable multi-thread decoding when refreshctx is equal to 0

In vp9_decode_frame function, ff_thread_finish_setup is not called
when refreshctx is equal to 0, and the next decoding thread can not
start work until the cunrrent frame has been decoded completely. So
ff_thread_finish_setup needs to be called to enable Multi-thread
decoding in this condition.

Signed-off-by: Di Wu <di1028.wu@samsung.com>
Signed-off-by: Reynaldo H. Verdejo Pinochet <reynaldo@osg.samsung.com>
libavcodec/ppc/me_cmp.c : fix sad16_altivec() sse16_altivec() sad16_xy2_altivec() sad16_x2_altivec() sad16_y2_altivec() sad8_altivec() for POWER LE

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
libavcodec/ppc/hpeldsp_altivec.c : fix ff_put_pixels16_altivec() for POWER LE

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