Remove @import statements and replace w/ headers

Author: Brandon Sneed

Segment-Firebase/Classes/SEGFirebaseIntegration.m

@@ -1,12 +1,12 @@
 #import "SEGFirebaseIntegration.h"
 
-@import FirebaseCore;
-@import FirebaseAnalytics;
+#import <FirebaseCore/FirebaseCore.h>
+#import <FirebaseAnalytics/FirebaseAnalytics.h>
 
 #if defined(__has_include) && __has_include(<Analytics/SEGAnalytics.h>)
 #import <Analytics/SEGAnalyticsUtils.h>
 #else
-@import Segment;
+#import <Segment/Segment.h>
 #endif
 
 

Segment-Firebase/Classes/SEGFirebaseIntegrationFactory.h

@@ -3,7 +3,7 @@
 #if defined(__has_include) && __has_include(<Analytics/SEGAnalytics.h>)
 #import <Analytics/SEGIntegrationFactory.h>
 #else
-@import Segment;
+#import <Segment/Segment.h>
 #endif