Add DTS_INC to the CFLAGS for DTS. This is only set by external configure

programs (such as the MPlayer one) and thus somewhat hackish.  We already
do this for things like MLIB_INC and IPP_INC so it should be acceptable.

Originally committed as revision 4659 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -240,6 +240,7 @@ EXTRALIBS += -L../libavutil -lavutil$(BUILDSUF)
 # currently using libdts for dts decoding
 ifeq ($(CONFIG_DTS),yes)
 OBJS+= dtsdec.o
+CFLAGS += $(DTS_INC)
 endif
 
 ifeq ($(CONFIG_FAAD),yes)