dca: Rename dca.c ---> dcadec.c

This will allow adding dca.c with tables used from other files.

libavcodec/Makefile

@@ -119,8 +119,8 @@ OBJS-$(CONFIG_CLJR_ENCODER)            += cljr.o
 OBJS-$(CONFIG_COOK_DECODER)            += cook.o
 OBJS-$(CONFIG_CSCD_DECODER)            += cscd.o
 OBJS-$(CONFIG_CYUV_DECODER)            += cyuv.o
-OBJS-$(CONFIG_DCA_DECODER)             += dca.o synth_filter.o dcadsp.o \
-                                          dca_parser.o
+OBJS-$(CONFIG_DCA_DECODER)             += dcadec.o dcadsp.o            \
+                                          dca_parser.o synth_filter.o
 OBJS-$(CONFIG_DFA_DECODER)             += dfa.o
 OBJS-$(CONFIG_DNXHD_DECODER)           += dnxhddec.o dnxhddata.o
 OBJS-$(CONFIG_DNXHD_ENCODER)           += dnxhdenc.o dnxhddata.o       \