Fix memory leak of function attribute hash table

Found while implementing php#7921:

> ==56540== 272 (56 direct, 216 indirect) bytes in 1 blocks are definitely lost in loss record 8 of 8
> ==56540==    at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==56540==    by 0x6D2C62: __zend_malloc (zend_alloc.c:3055)
> ==56540==    by 0x73E874: zend_add_attribute (zend_attributes.c:282)
> ==56540==    by 0x65BE40: zend_add_parameter_attribute (zend_attributes.h:104)
> ==56540==    by 0x65C760: zm_startup_password (password.c:452)
> ==56540==    by 0x592AC7: zm_startup_basic (basic_functions.c:364)
> ==56540==    by 0x71B18D: zend_startup_module_ex (zend_API.c:2202)
> ==56540==    by 0x71B1EC: zend_startup_module_zval (zend_API.c:2217)
> ==56540==    by 0x72CF48: zend_hash_apply (zend_hash.c:2011)
> ==56540==    by 0x71B8F0: zend_startup_modules (zend_API.c:2328)
> ==56540==    by 0x66CE1B: php_module_startup (main.c:2256)
> ==56540==    by 0x887FC8: php_cli_startup (php_cli.c:409)

Author: TimWolla

Zend/zend_opcode.c

@@ -153,6 +153,12 @@ ZEND_API void zend_function_dtor(zval *zv)
 		ZEND_ASSERT(function->common.function_name);
 		zend_string_release_ex(function->common.function_name, 1);
 
+		if (function->common.attributes) {
+			zend_hash_destroy(function->common.attributes);
+			free(function->common.attributes);
+			function->common.attributes = NULL;
+		}
+
 		/* For methods this will be called explicitly. */
 		if (!function->common.scope) {
 			zend_free_internal_arg_info(&function->internal_function);