Merge branch 'PHP-7.4'

* PHP-7.4:
  Fix length inconsistency in mb_convert_encoding

Author: nikic

ext/mbstring/mbstring.c

@@ -2852,7 +2852,7 @@ PHP_FUNCTION(mb_convert_encoding)
 
 					if ( _from_encodings) {
 						l = strlen(_from_encodings);
-						n = strlen(ZSTR_VAL(encoding_str));
+						n = ZSTR_LEN(encoding_str);
 						_from_encodings = erealloc(_from_encodings, l+n+2);
 						memcpy(_from_encodings + l, ",", 1);
 						memcpy(_from_encodings + l + 1, ZSTR_VAL(encoding_str), ZSTR_LEN(encoding_str) + 1);

ext/mbstring/tests/bug79149.phpt

@@ -8,6 +8,7 @@ if (!extension_loaded('mbstring')) die('skip mbstring extension not available');
 <?php
 var_dump(mb_convert_encoding("", "UTF-8", [0]));
 var_dump(mb_convert_encoding('foo', 'UTF-8', array(['bar'], ['baz'])));
+var_dump(mb_convert_encoding('foo', 'UTF-8', array("foo\0bar")));
 ?>
 --EXPECTF--
 Warning: mb_convert_encoding(): Illegal character encoding specified in %s on line %d
@@ -19,3 +20,6 @@ Warning: Array to string conversion in %s on line %d
 
 Warning: mb_convert_encoding(): Illegal character encoding specified in %s on line %d
 string(3) "foo"
+
+Warning: mb_convert_encoding(): Illegal character encoding specified in %s on line %d
+string(3) "foo"