ext/gettext/tests: fix bind_textdomain_codeset() return values under musl

The musl implementation of bind_textdomain_codeset() always returns
NULL. The POSIX-correctness of this is debatable, but it is roughly
equivalent to correct, because musl only support UTF-8, so the NULL
value indicating that the codeset is unchanged from the locale's
codeset (UTF-8) is accurate.

PHP's bind_textdomain_codeset() function however treats NULL as
failure, unconditionally:

  * php/doc-en#4311
  * #17163

This unfortunately causes false to be returned consistently on musl --
even when nothing unexpected has happened -- and naturally this is
affecting several tests. For now we change two tests to accept "false"
in addition to "UTF-8" so that they may pass on musl. If PHP's
bind_textdomain_codeset() is updated to differentiate between NULL and
NULL-with-errno-set, these tests can also be updated once again to
reject the NULL-with-errno result.

This partially addresses GH #13696

Author: orlitzky

ext/gettext/tests/bug53251.phpt

@@ -12,14 +12,22 @@ var_dump(is_string(bindtextdomain('foo', null)));
 $dir = bindtextdomain('foo', '.');
 var_dump(bindtextdomain('foo', null) === $dir);
 
+// bind_textdomain_codeset() always returns false on musl
+// because musl only supports UTF-8. For more information:
+//
+//   * https://github.com/php/doc-en/issues/4311,
+//   * https://github.com/php/php-src/issues/17163
+//
 var_dump(bind_textdomain_codeset('foo', null));
-var_dump(bind_textdomain_codeset('foo', 'UTF-8'));
-var_dump(bind_textdomain_codeset('foo', null));
+$result = bind_textdomain_codeset('foo', 'UTF-8');
+var_dump(!$result or $result === "UTF-8");
+$result = bind_textdomain_codeset('foo', null);
+var_dump(!$result or $result === "UTF-8");
 
 ?>
 --EXPECT--
 bool(true)
 bool(true)
 bool(false)
-string(5) "UTF-8"
-string(5) "UTF-8"
+bool(true)
+bool(true)

ext/gettext/tests/gettext_bind_textdomain_codeset-retval.phpt

@@ -15,14 +15,22 @@ gettext
     } catch (ValueError $e) {
 	    echo $e->getMessage() . PHP_EOL;
     }
-    var_dump(bind_textdomain_codeset('messages', "UTF-8"));
+
+    // bind_textdomain_codeset() always returns false on musl
+    // because musl only supports UTF-8. For more information:
+    //
+    //   * https://github.com/php/doc-en/issues/4311,
+    //   * https://github.com/php/php-src/issues/17163
+    //
+    $result = bind_textdomain_codeset('messages', "UTF-8");
+    var_dump(!$result or $result === "UTF-8");
 
     echo "Done\n";
 ?>
 --EXPECT--
 bind_textdomain_codeset(): Argument #1 ($domain) must not be empty
 bind_textdomain_codeset(): Argument #1 ($domain) must not be empty
-string(5) "UTF-8"
+bool(true)
 Done
 --CREDITS--
 Florian Holzhauer [email protected]