Make the Instagram app compile again

Summary:
Wrap iOS 14 SDK code in a `#if/#endif` so that the Instagram app compiles again

Changelog: [Internal]

Reviewed By: PeteTheHeat

Differential Revision: D23948336

fbshipit-source-id: 67e6ee48d1951ae405c12b4ad39cf8c9817df627

React/Views/RCTDatePicker.m

@@ -7,9 +7,20 @@
 
 #import "RCTDatePicker.h"
 
+#import <Availability.h>
+#import <AvailabilityInternal.h>
+
 #import "RCTUtils.h"
 #import "UIView+React.h"
 
+#ifndef __IPHONE_14_0
+  #define __IPHONE_14_0 140000
+#endif // __IPHONE_14_0
+
+#ifndef RCT_IOS_14_0_SDK_OR_LATER
+  #define RCT_IOS_14_0_SDK_OR_LATER (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_14_0)
+#endif // RCT_IOS_14_0_SDK_OR_LATER
+
 @interface RCTDatePicker ()
 
 @property (nonatomic, copy) RCTBubblingEventBlock onChange;
@@ -25,9 +36,11 @@ - (instancetype)initWithFrame:(CGRect)frame
     [self addTarget:self action:@selector(didChange) forControlEvents:UIControlEventValueChanged];
     _reactMinuteInterval = 1;
 
+#if RCT_IOS_14_0_SDK_OR_LATER
     if (@available(iOS 14, *)) {
       self.preferredDatePickerStyle = UIDatePickerStyleWheels;
     }
+#endif // RCT_IOS_14_0_SDK_OR_LATER
   }
   return self;
 }