Revert faulty commit to avoid undefined behaviour:
https://bugs.freedesktop.org/show_bug.cgi?id=104325

Taken from this upstream commit:
https://cgit.freedesktop.org/cairo/commit/?h=1.14&id=2acc4382c54bd8239361ceed14423412a343d311

diff --git a/src/cairo-bentley-ottmann-rectangular.c b/src/cairo-bentley-ottmann-rectangular.c
index cb2e30c..5541bdc 100644
--- a/src/cairo-bentley-ottmann-rectangular.c
+++ b/src/cairo-bentley-ottmann-rectangular.c
@@ -593,12 +593,6 @@ sweep_line_insert (sweep_line_t	*sweep, rectangle_t *rectangle)
     pqueue_push (sweep, rectangle);
 }
 
-static int
-sweep_line_setjmp (sweep_line_t *sweep_line)
-{
-    return setjmp (sweep_line->unwind);
-}
-
 static cairo_status_t
 _cairo_bentley_ottmann_tessellate_rectangular (rectangle_t	**rectangles,
 					       int			  num_rectangles,
@@ -615,7 +609,7 @@ _cairo_bentley_ottmann_tessellate_rectangular (rectangle_t	**rectangles,
 		     rectangles, num_rectangles,
 		     fill_rule,
 		     do_traps, container);
-    if ((status = sweep_line_setjmp (&sweep_line)))
+    if ((status = setjmp (sweep_line.unwind)))
 	return status;
 
     rectangle = rectangle_pop_start (&sweep_line);
diff --git a/src/cairo-png.c b/src/cairo-png.c
index e64b14a..068617d 100644
--- a/src/cairo-png.c
+++ b/src/cairo-png.c
@@ -158,14 +158,6 @@ png_simple_warning_callback (png_structp png,
      */
 }
 
-static int
-png_setjmp (png_struct *png)
-{
-#ifdef PNG_SETJMP_SUPPORTED
-    return setjmp (png_jmpbuf (png));
-#endif
-    return 0;
-}
 
 /* Starting with libpng-1.2.30, we must explicitly specify an output_flush_fn.
  * Otherwise, we will segfault if we are writing to a stream. */
@@ -237,8 +229,10 @@ write_png (cairo_surface_t	*surface,
 	goto BAIL4;
     }
 
-    if (png_setjmp (png))
+#ifdef PNG_SETJMP_SUPPORTED
+    if (setjmp (png_jmpbuf (png)))
 	goto BAIL4;
+#endif
 
     png_set_write_fn (png, closure, write_func, png_simple_output_flush_fn);
 
@@ -577,11 +571,12 @@ read_png (struct png_read_closure_t *png_closure)
     png_set_read_fn (png, png_closure, stream_read_func);
 
     status = CAIRO_STATUS_SUCCESS;
-
-    if (png_setjmp (png)) {
+#ifdef PNG_SETJMP_SUPPORTED
+    if (setjmp (png_jmpbuf (png))) {
 	surface = _cairo_surface_create_in_error (status);
 	goto BAIL;
     }
+#endif
 
     png_read_info (png, info);