Add missing SKIPIFs in exif tests

Author: villfa

ext/exif/tests/duplicate_copyright_tag_leak.phpt

@@ -1,5 +1,11 @@
 --TEST--
 OSS-Fuzz #17474: Memory leak on duplicate Copyright tags
+--SKIPIF--
+<?php
+if (!extension_loaded('exif')) {
+    die('skip exif extension not available');
+}
+?>
 --FILE--
 <?php
 

ext/exif/tests/tag_with_illegal_zero_components.phpt

@@ -1,5 +1,11 @@
 --TEST--
 OSS-Fuzz #17163: Out-of-bounds read due to tag with zero components
+--SKIPIF--
+<?php
+if (!extension_loaded('exif')) {
+    die('skip exif extension not available');
+}
+?>
 --FILE--
 <?php
 

ext/exif/tests/temporary_buffer_leak.phpt

@@ -1,5 +1,11 @@
 --TEST--
 OSS-Fuzz: Temporary buffer leak in tag reading
+--SKIPIF--
+<?php
+if (!extension_loaded('exif')) {
+    die('skip exif extension not available');
+}
+?>
 --FILE--
 <?php
 

ext/exif/tests/zero_length_makernote_leak.phpt

@@ -1,5 +1,11 @@
 --TEST--
 OSS-Fuzz: Memory leak for zero-length MAKERNOTE
+--SKIPIF--
+<?php
+if (!extension_loaded('exif')) {
+    die('skip exif extension not available');
+}
+?>
 --FILE--
 <?php