Add missing Makefile dependencies to CONFIG_SNOW_ENCODER.

Fixes build with --disable-encoders --enable-encoder=snow.
This fixes MPlayer build with --disable-mencoder.

Originally committed as revision 21259 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -271,7 +271,8 @@ OBJS-$(CONFIG_SMC_DECODER)             += smc.o
 OBJS-$(CONFIG_SNOW_DECODER)            += snow.o rangecoder.o
 OBJS-$(CONFIG_SNOW_ENCODER)            += snow.o rangecoder.o motion_est.o \
                                           ratecontrol.o h263.o             \
-                                          mpegvideo.o error_resilience.o
+                                          mpegvideo.o error_resilience.o   \
+                                          ituh263enc.o mpegvideo_enc.o
 OBJS-$(CONFIG_SOL_DPCM_DECODER)        += dpcm.o
 OBJS-$(CONFIG_SONIC_DECODER)           += sonic.o
 OBJS-$(CONFIG_SONIC_ENCODER)           += sonic.o