[qfcc] Add a function to create typed zero expressions

Sometimes, nil's untyped 0 isn't really suitable.

tools/qfcc/include/expr.h

@@ -562,6 +562,15 @@ expr_t *new_args_expr (void);
 */
 expr_t *new_value_expr (ex_value_t *value);
 
+/** Create a new typed zero value expression node.
+
+	Similar to new_nil_expr, but is 0 of a specific type.
+
+	\param type		The type to use for the zero.
+	\return			The new value expression.
+*/
+expr_t *new_zero_expr (struct type_s *type);
+
 /**	Create a new symbol expression node from a name.
 
 	\param name		The name for the symbol.

tools/qfcc/source/expr.c

@@ -772,6 +772,13 @@ new_value_expr (ex_value_t *value)
 	return e;
 }
 
+expr_t *
+new_zero_expr (type_t *type)
+{
+	pr_type_t zero[type_size (type)] = {};
+	return new_value_expr (new_type_value (type, zero));
+}
+
 expr_t *
 new_name_expr (const char *name)
 {