Migrate the link_darwin_amd64.go and control.go files back; fixed up errors in the C files and util.go.

control.go

@@ -6,7 +6,7 @@ import (
 	"unsafe"
 )
 
-// #include "ui.h"
+// #include "pkgui.h"
 import "C"
 
 // no need to lock this; only the GUI thread can access it

pkgui.c

@@ -1,6 +1,6 @@
 // 26 august 2018
 #include "pkgui.h"
-#include "xxxxx"
+#include "_cgo_export.h"
 
 uiInitOptions *pkguiAllocInitOptions(void)
 {

pkgui.h

@@ -1,5 +1,5 @@
 // 12 august 2018
-#include <stdio.h>
+#include <stdlib.h>
 #include "ui.h"
 
 // main.go

util.go

@@ -12,6 +12,7 @@ import "C"
 //export pkguiAlloc
 func pkguiAlloc(n C.size_t) unsafe.Pointer {
 	// cgo turns C.malloc() into a panic-on-OOM version; use it
+	// TODO make sure it zero-initializes too
 	return C.malloc(n)
 }