Fix brittle test

This test is easily tripped by former test runs with other PHP
versions.  To avoid such false positives, we check that there is at
least one respective OPcache file, and that all found OPcache user ID
folders have exactly 32 hexadecimal digits.

ext/opcache/tests/bug78189.phpt

@@ -14,9 +14,16 @@ opcache.file_cache_only=1
 <?php
 $tmpdir = sys_get_temp_dir();
 $pattern = $tmpdir . '/*/*/' . str_replace(':', '', __DIR__) . '/bug78189.php.bin';
-foreach (glob($pattern) as $filename) {
-    var_dump(preg_match('~/[0-9a-f]{32}/~', substr($filename, strlen($tmpdir), 34)));
+$filenames = glob($pattern);
+if (count($filenames)) {
+    foreach ($filenames as $filename) {
+        $part = substr($filename, strlen($tmpdir), 34);
+        if (!preg_match('~/[0-9a-f]{32}/~', $part)) {
+            echo "invalid opcache folder: $part\n";
+        }
+    }
+} else {
+    echo "no opcache file found!\n";
 }
 ?>
 --EXPECT--
-int(1)