ext/gd/tests: backport optional PNG support

- Three of our gd tests could be skipped with a message about requiring
bundled GD, but those tests don't actually require bundled GD. We
update the messages to mention the specific functions that are
required.

- add SKIPIF stanzas for missing PNG support

The bundled libgd always has PNG support, but an external one may not.

- imagerotate() is always available

Following 59ec80c, the imagerotate() function is always available. We
may therefore remove its function_exists() checks without harm.

close GH-17894

Author: orlitzky

ext/gd/tests/bug22544-mb.phpt

@@ -2,6 +2,12 @@
 Bug #22544 (TrueColor transparency in PNG images).
 --EXTENSIONS--
 gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_PNG)) {
+    die("skip No PNG support");
+}
+?>
 --FILE--
 <?php
     $image = imageCreateTruecolor(640, 100);

ext/gd/tests/bug22544.phpt

@@ -2,6 +2,12 @@
 Bug #22544 (TrueColor transparency in PNG images).
 --EXTENSIONS--
 gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_PNG)) {
+    die("skip No PNG support");
+}
+?>
 --FILE--
 <?php
     $image = imageCreateTruecolor(640, 100);

ext/gd/tests/bug24155.phpt

@@ -4,7 +4,9 @@ Bug #24155 (gdImageRotate270 rotation problem).
 gd
 --SKIPIF--
 <?php
-    if (!function_exists("imagerotate")) die("skip requires bundled GD library\n");
+    if (!(imagetypes() & IMG_PNG)) {
+        die("skip No PNG support");
+    }
 ?>
 --FILE--
 <?php

ext/gd/tests/bug27582_1.phpt

@@ -2,6 +2,12 @@
 Bug #27582 (ImageFillToBorder() on alphablending image looses alpha on fill color)
 --EXTENSIONS--
 gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_PNG)) {
+    die("skip No PNG support");
+}
+?>
 --FILE--
 <?php
 $dest = dirname(realpath(__FILE__)) . '/bug27582.png';

ext/gd/tests/bug39366.phpt

@@ -2,10 +2,6 @@
 Bug #39366 (imagerotate does not respect alpha with angles>45)
 --EXTENSIONS--
 gd
---SKIPIF--
-<?php
-    if (!function_exists("imagerotate")) die("skip requires bundled GD library\n");
-?>
 --FILE--
 <?php
 

ext/gd/tests/bug39780_extern.phpt

@@ -5,6 +5,9 @@ gd
 --SKIPIF--
 <?php
     if (GD_BUNDLED) die("skip requires extern GD\n");
+    if (!(imagetypes() & IMG_PNG)) {
+        die("skip No PNG support");
+    }
 ?>
 --FILE--
 <?php

ext/gd/tests/bug43073.phpt

@@ -5,6 +5,9 @@ gd
 --SKIPIF--
 <?php
     if(!function_exists('imagettftext')) die('skip imagettftext() not available');
+    if (!(imagetypes() & IMG_PNG)) {
+        die("skip No PNG support");
+    }
 ?>
 --FILE--
 <?php

ext/gd/tests/bug43475.phpt

@@ -7,6 +7,9 @@ gd
     if (!GD_BUNDLED && version_compare(GD_VERSION, '2.2.2', '<')) {
         die("skip test requires GD 2.2.2 or higher");
     }
+    if (!(imagetypes() & IMG_PNG)) {
+        die("skip No PNG support");
+    }
 ?>
 --FILE--
 <?php

ext/gd/tests/bug43828.phpt

@@ -7,6 +7,9 @@ gd
 if (!GD_BUNDLED && version_compare(GD_VERSION, '2.2.2', '<')) {
     die("skip test requires GD 2.2.2 or higher");
 }
+if (!(imagetypes() & IMG_PNG)) {
+    die("skip No PNG support");
+}
 ?>
 --FILE--
 <?php

ext/gd/tests/bug45799.phpt

@@ -2,6 +2,12 @@
 Bug #45799 (imagepng() crashes on empty image).
 --EXTENSIONS--
 gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_PNG)) {
+    die("skip No PNG support");
+}
+?>
 --FILE--
 <?php
 $img = imagecreate(500,500);