Have EXTRALIBS appear after other link options, fixes shared build on Cygwin.

based on patch by Marcus Engene, ffmpeg AATT engene DDOOTT se

Originally committed as revision 5295 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/Makefile

@@ -293,7 +293,7 @@ OBJS+= liba52/bit_allocate.o liba52/bitstream.o liba52/downmix.o \
 endif
 endif
 
-EXTRALIBS += -L../libavutil -lavutil$(BUILDSUF)
+EXTRALIBS := -L../libavutil -lavutil$(BUILDSUF) $(EXTRALIBS)
 
 # currently using libdts for dts decoding
 ifeq ($(CONFIG_DTS),yes)

libavformat/Makefile

@@ -66,7 +66,7 @@ ifeq ($(CONFIG_AUDIO_OSS),yes)
 OBJS+= audio.o
 endif
 
-EXTRALIBS += -L../libavutil -lavutil$(BUILDSUF) -lavcodec$(BUILDSUF) -L../libavcodec
+EXTRALIBS := -L../libavutil -lavutil$(BUILDSUF) -lavcodec$(BUILDSUF) -L../libavcodec $(EXTRALIBS)
 
 ifeq ($(CONFIG_AUDIO_BEOS),yes)
 CPPOBJS+= beosaudio.o