From: inkscape upstream
Fix compilation against libpng-1.5

=== modified file 'src/extension/internal/pdfinput/svg-builder.cpp'
--- src/extension/internal/pdfinput/svg-builder.cpp	2011-10-27 04:55:51 +0000
+++ src/extension/internal/pdfinput/svg-builder.cpp	2011-10-29 20:34:00 +0000
@@ -1481,7 +1481,7 @@
         return NULL;
     }
     // Set error handler
-    if (setjmp(png_ptr->jmpbuf)) {
+    if (setjmp(png_jmpbuf(png_ptr))) {
         png_destroy_write_struct(&png_ptr, &info_ptr);
         return NULL;
     }

=== modified file 'src/helper/png-write.cpp'
--- src/helper/png-write.cpp	2011-08-07 10:53:12 +0000
+++ src/helper/png-write.cpp	2011-10-29 20:34:00 +0000
@@ -166,8 +166,8 @@
     /* Set error handling.  REQUIRED if you aren't supplying your own
      * error hadnling functions in the png_create_write_struct() call.
      */
-    if (setjmp(png_ptr->jmpbuf)) {
-        /* If we get here, we had a problem reading the file */
+    if (setjmp(png_jmpbuf(png_ptr))) {
+        // If we get here, we had a problem reading the file
         fclose(fp);
         png_destroy_write_struct(&png_ptr, &info_ptr);
         return false;