Remove use of some deprecated code and cleanup other macOS code

src/core/mac_utilities.mm

@@ -0,0 +1,36 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2019, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * Strawberry is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Strawberry is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "config.h"
+
+#include <QtGlobal>
+
+#import <Foundation/Foundation.h>
+#import <Foundation/NSProcessInfo.h>
+
+namespace Utilities {
+
+qint32 GetMacOsVersion() {
+
+  NSOperatingSystemVersion version = [ [NSProcessInfo processInfo] operatingSystemVersion];
+  return version.minorVersion;
+
+}
+
+}  // namespace Utilities