FIX: OSX disable app-nap during serial comm (@anticat)

https://github.com/Proxmark/proxmark3/pull/687

client/util_darwin.c

@@ -0,0 +1,40 @@
+//-----------------------------------------------------------------------------
+// (c) 2018 AntiCat
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// macOS framework bindings
+//-----------------------------------------------------------------------------
+
+#import "util_darwin.h"
+
+#import <Foundation/NSString.h>
+#import <Foundation/NSProcessInfo.h>
+
+static id activity = nil;
+
+//OS X Version 10.10 is defined in OS X 10.10 and later
+#if defined(MAC_OS_X_VERSION_10_10)
+void disableAppNap(const char* reason) {
+	if(activity == nil) {
+		//NSLog(@"disableAppNap: %@", @(reason));
+		activity = [[NSProcessInfo processInfo] beginActivityWithOptions:NSActivityBackground reason:@(reason)];
+		[activity retain];
+	}
+}
+
+void enableAppNap() {
+	if(activity != nil) {
+		//NSLog(@"enableAppNap");
+		[[NSProcessInfo processInfo] endActivity:activity];
+		[activity release];
+		activity = nil;
+	}
+}
+
+#else
+void disableAppNap(const char* reason) { }
+void enableAppNap() { }
+#endif