contrib: patch zvbi for libpng15 api

contrib/src/zvbi/rules.mak

@@ -17,6 +17,7 @@ zvbi: zvbi-$(ZVBI_VERSION).tar.bz2 .sum-zvbi
 	$(UNPACK)
 	$(APPLY) $(SRC)/zvbi/zvbi-ssize_max.patch
 	$(APPLY) $(SRC)/zvbi/zvbi-ioctl.patch
+	$(APPLY) $(SRC)/zvbi/zvbi-png15.patch
 ifdef HAVE_WIN32
 	$(APPLY) $(SRC)/zvbi/zvbi-win32.patch
 endif

contrib/src/zvbi/zvbi-png15.patch

+--- zvbi.orig/src/exp-gfx.c	2011-11-19 17:48:45.953865404 -0500
++++ zvbi/src/exp-gfx.c	2011-11-19 17:53:55.543400579 -0500
+@@ -1672,11 +1672,11 @@
+ 	char title[80];
+ 	unsigned int i;
+ 
+-	if (setjmp (png_ptr->jmpbuf))
++	if (setjmp (png_jmpbuf(png_ptr)))
+ 		return FALSE;
+ 
+ 	png_set_write_fn (png_ptr,
+-			  (voidp) gfx,
++			  (png_voidp) gfx,
+ 			  write_data,
+ 			  flush_data);
+