Build objective-c files only on Darwin

Author: MatteoPologruto

certificates/certificates.h renamed to certificates/certificates_darwin.h

@@ -1,6 +1,6 @@
 #import <Foundation/Foundation.h>
 #import <AppKit/AppKit.h>
-#include "certificates.h"
+#include "certificates_darwin.h"
 
 // Used to return error strings (as NSString) as a C-string to the Go code.
 const char *toErrorString(NSString *errString) {

certificates/certificates.m renamed to certificates/certificates_darwin.m

@@ -24,7 +24,7 @@ package certificates
 #cgo LDFLAGS: -framework Foundation -framework Security -framework AppKit -ld_classic
 
 #import <Foundation/Foundation.h>
-#include "certificates.h"
+#include "certificates_darwin.h"
 */
 import "C"
 import (

certificates/install_darwin.go

@@ -17,20 +17,6 @@
 
 package certificates
 
-/*
-// Importing "certificates.h" here even if it is not used avoids building errors on Ubuntu and Windows.
-
-// Explicitly tell the GCC compiler that the language is Objective-C.
-#cgo CFLAGS: -x objective-c
-
-// Pass the list of macOS frameworks needed by this piece of Objective-C code.
-// The "-ld_classic" is needed to avoid a wrong warning about duplicate libraries when building with XCode 15.
-#cgo LDFLAGS: -framework Foundation -framework Security -framework AppKit -ld_classic
-
-#import <Foundation/Foundation.h>
-#include "certificates.h"
-*/
-
 import (
 	"errors"
 	"time"