Move iOS Versions from Signal-iOS

// FREEBIE

src/Messages/OWSMessageSender.m

@@ -42,11 +42,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(major, minor)                                                          \
-    ([[NSProcessInfo processInfo]                                                                                      \
-        isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){                                                    \
-                                            .majorVersion = major, .minorVersion = minor, .patchVersion = 0 }])
-
 /**
  * OWSSendMessageOperation encapsulates all the work associated with sending a message, e.g. uploading attachments,
  * getting proper keys, and retrying upon failure.

src/TSPrefix.h

@@ -4,6 +4,7 @@
 
 #import "Asserts.h"
 #import "Constraints.h"
+#import "iOSVersions.h"
 #import "OWSAnalytics.h"
 #import "OWSDispatch.h"
 #import <CocoaLumberjack/CocoaLumberjack.h>

src/Util/iOSVersions.h

@@ -0,0 +1,9 @@
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#include <Availability.h>
+
+#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(major, minor) \
+    ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){.majorVersion = major, .minorVersion = minor, .patchVersion = 0}])