ARM: move NEON H264 chroma mc to a separate file

This allows sharing code with the rv40 version of these functions.
Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/arm/Makefile

@@ -54,6 +54,7 @@ NEON-OBJS-$(CONFIG_RDFT)               += arm/rdft_neon.o               \
 
 NEON-OBJS-$(CONFIG_H264DSP)            += arm/h264dsp_neon.o            \
                                           arm/h264idct_neon.o           \
+                                          arm/h264cmc_neon.o            \
 
 NEON-OBJS-$(CONFIG_H264PRED)           += arm/h264pred_neon.o           \