get svn version when using separate build tree

Originally committed as revision 5539 to svn://svn.ffmpeg.org/ffmpeg/trunk

Makefile

@@ -92,7 +92,7 @@ ffplay_g$(EXESUF): ffplay.o cmdutils.o .libs
 
 .PHONY: version.h
 version.h:
-	$(SRC_PATH)/version.sh
+	$(SRC_PATH)/version.sh "$(SRC_PATH)"
 
 output_example$(EXESUF): output_example.o .libs
 	$(CC) $(FFLIBDIRS) $(LDFLAGS) -o $@ output_example.o $(FFLIBS) $(EXTRALIBS)

version.sh

 #!/bin/sh
 
-svn_revision=`svn info 2> /dev/null | grep Revision | cut -d' ' -f2`
+svn_revision=`cd "$1" && svn info 2> /dev/null | grep Revision | cut -d' ' -f2`
 test $svn_revision || svn_revision=UNKNOWN
 
 NEW_REVISION="#define FFMPEG_VERSION \"SVN-r$svn_revision\""