matchbox-lib: patch up support for libpng 1.5+

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/matchbox/matchbox-lib/matchbox-lib-1.9-libpng15.patch

@@ -0,0 +1,26 @@
+Support for libpng 1.5+ shamelessly taken from Gentoo.
+
+Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
+
+--- a/libmb/mbpixbuf.c
++++ b/libmb/mbpixbuf.c
+@@ -247,7 +247,7 @@
+     return NULL;
+   }
+ 
+-  if ( setjmp( png_ptr->jmpbuf ) ) {
++  if ( setjmp( png_jmpbuf(png_ptr) ) ) {
+     png_destroy_read_struct( &png_ptr, &info_ptr, NULL);
+     fclose(fd);
+     return NULL;
+@@ -269,8 +269,8 @@
+       ( color_type == PNG_COLOR_TYPE_GRAY_ALPHA ))
+     png_set_gray_to_rgb(png_ptr);
+  
+-  if ( info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA 
+-       || info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA
++  if ( color_type == PNG_COLOR_TYPE_RGB_ALPHA 
++       || color_type == PNG_COLOR_TYPE_GRAY_ALPHA
+        )
+     *has_alpha = 1;
+   else