Fix VP8 decoder dependencies

This reverts rev 24674 - the VP8 decoder actually depends on cabac.o.
vp8.c includes vp56.h, which includes cabac.h, which has inline functions
that reference tables from cabac.c.

This fixes compilation with --disable-everything --enable-decoder=vp8.

Originally committed as revision 24692 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -379,7 +379,7 @@ OBJS-$(CONFIG_VP5_DECODER)             += vp5.o vp56.o vp56data.o vp56dsp.o \
                                           vp3dsp.o cabac.o
 OBJS-$(CONFIG_VP6_DECODER)             += vp6.o vp56.o vp56data.o vp56dsp.o \
                                           vp3dsp.o vp6dsp.o huffman.o cabac.o
-OBJS-$(CONFIG_VP8_DECODER)             += vp8.o vp8dsp.o
+OBJS-$(CONFIG_VP8_DECODER)             += vp8.o vp8dsp.o cabac.o
 OBJS-$(CONFIG_VQA_DECODER)             += vqavideo.o
 OBJS-$(CONFIG_WAVPACK_DECODER)         += wavpack.o
 OBJS-$(CONFIG_WMAPRO_DECODER)          += wmaprodec.o wma.o