Fix -Wreturn-local-addr warning

zend_string_dup() can return the original string if it is interned.
Of course, the string can't be interned here, but GCC doesn't know
that and throws a warning in release builds.

Replace zend_string_dup() (which is a bad API anyway) with a direct
call to zend_string_init(), which makes it more obvious that the
original alloca'd string cannot be reused.

Author: nikic

ext/standard/browscap.c

@@ -249,7 +249,7 @@ static zend_string *browscap_intern_str_ci(
 	if (interned) {
 		zend_string_addref(interned);
 	} else {
-		interned = zend_string_dup(lcname, persistent);
+		interned = zend_string_init(ZSTR_VAL(lcname), ZSTR_LEN(lcname), persistent);
 		if (persistent) {
 			interned = zend_new_interned_string(interned);
 		}