Add true global for mixed type

Author: Girgias

Zend/zend_compile.c

@@ -84,6 +84,8 @@ static inline uint32_t zend_alloc_cache_slot(void) {
 	return zend_alloc_cache_slots(1);
 }
 
+const zend_type zend_mixed_type = { NULL, MAY_BE_ANY };
+
 ZEND_API zend_op_array *(*zend_compile_file)(zend_file_handle *file_handle, int type);
 ZEND_API zend_op_array *(*zend_compile_string)(zend_string *source_string, const char *filename, zend_compile_position position);
 

Zend/zend_compile.h

@@ -53,6 +53,7 @@
 
 typedef struct _zend_op_array zend_op_array;
 typedef struct _zend_op zend_op;
+extern const zend_type zend_mixed_type;
 
 /* On 64-bit systems less optimal, but more compact VM code leads to better
  * performance. So on 32-bit systems we use absolute addresses for jump