libgccjit: Fix UB in gcc_jit_context_new_array_constructor

Author: antoyo

gcc/jit/libgccjit.cc

@@ -1732,7 +1732,7 @@ gcc_jit_context_new_array_constructor (gcc_jit_context *ctxt,
 	"'values' NULL with non-zero 'num_values'");
 
       gcc::jit::recording::array_type *arr_type =
-	reinterpret_cast<gcc::jit::recording::array_type*>(type);
+	type->dyn_cast_array_type ();
       size_t n_el = arr_type->num_elements ();
 
       RETURN_NULL_IF_FAIL_PRINTF2 (