Some (Solaris) gcc versions apparently output a comment as first line

when generating dependencies. Make sure to remove this in DEPEND_CMD.
extracted in a modified form from a gstreamer patch for FFmpeg

Originally committed as revision 13530 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -955,7 +955,7 @@ SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
 LIB_INSTALL_EXTRA_CMD='$(RANLIB) "$(LIBDIR)/$(LIBNAME)"'
 
 # gcc stupidly only outputs the basename of targets with -MM
-DEPEND_CMD='$(CC) $(CFLAGS) -MM -MG $< | sed "1s,^,$(@D)/,"'
+DEPEND_CMD='$(CC) $(CFLAGS) -MM -MG $< | sed -e "/^\#.*/d" -e "1s,^,$(@D)/,"'
 
 # find source path
 source_path="`dirname \"$0\"`"