Fix typo that mistakenly slipped into previous commit:

CONFIG_MPEG_XVMC_DECODER was changed to CONFIG_MPEGVIDEO_XVMC_DECODER.
patch by Onur Küçük, onur delipenguen net

Originally committed as revision 20278 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -187,7 +187,7 @@ OBJS-$(CONFIG_MPC8_DECODER)            += mpc8.o mpc.o mpegaudiodec.o      \
                                           mpegaudiodata.o
 OBJS-$(CONFIG_MPEGVIDEO_DECODER)       += mpeg12.o mpeg12data.o \
                                           mpegvideo.o error_resilience.o
-OBJS-$(CONFIG_MPEGVIDEO_XVMC_DECODER)  += mpegvideo_xvmc.o
+OBJS-$(CONFIG_MPEG_XVMC_DECODER)       += mpegvideo_xvmc.o
 OBJS-$(CONFIG_MPEG1VIDEO_DECODER)      += mpeg12.o mpeg12data.o \
                                           mpegvideo.o error_resilience.o
 OBJS-$(CONFIG_MPEG1VIDEO_ENCODER)      += mpeg12enc.o mpegvideo_enc.o \