Generate g for today state of Go 1.18 (go1.17beta1-2522-g47db3bb443)
Compared to Go1.17 there are small number of changes in _defer struct.

Regenerated files stay without changes for Go1.17 and previous releases.

---- 8< ----
diff --git a/zruntime_g_go1.17.go b/zruntime_g_go1.18.go
index 7a76db6..5e2fafb 100644
--- a/zruntime_g_go1.17.go
+++ b/zruntime_g_go1.18.go
@@ -1,6 +1,6 @@
 // Code generated by g_typedef; DO NOT EDIT.

-// +build go1.17,!go1.18
+// +build go1.18,!go1.19

 package xruntime

@@ -115,7 +115,6 @@ type _panic struct {
 	goexit    bool
 }
 type _defer struct {
-	siz     int32 // includes both arguments and results
 	started bool
 	heap    bool
 	// openDefer indicates that this _defer is for a frame with open-coded
@@ -124,9 +123,9 @@ type _defer struct {
 	openDefer bool
 	sp        uintptr // sp at time of defer
 	pc        uintptr // pc at time of defer
-	fn        *funcval // can be nil for open-coded defers
+	fn        func()  // can be nil for open-coded defers
 	_panic    *_panic // panic that is running defer
-	link      *_defer
+	link      *_defer // next defer on G; can point to either heap or stack!

 	// If openDefer is true, the fields below record values about the stack
 	// frame and associated function that has the open-coded defer(s). sp