lavf: rename wv.c to wvdec.c

wv.c will be used for shared wavpack functions.

libavformat/Makefile

@@ -334,7 +334,7 @@ OBJS-$(CONFIG_WSAUD_DEMUXER)             += westwood_aud.o
 OBJS-$(CONFIG_WSVQA_DEMUXER)             += westwood_vqa.o
 OBJS-$(CONFIG_WTV_DEMUXER)               += wtv.o asfdec.o asf.o asfcrypt.o \
                                             avlanguage.o mpegts.o isom.o
-OBJS-$(CONFIG_WV_DEMUXER)                += wv.o apetag.o img2.o
+OBJS-$(CONFIG_WV_DEMUXER)                += wvdec.o apetag.o img2.o
 OBJS-$(CONFIG_XA_DEMUXER)                += xa.o
 OBJS-$(CONFIG_XMV_DEMUXER)               += xmv.o
 OBJS-$(CONFIG_XWMA_DEMUXER)              += xwma.o