Use macro instead of a constant

Author: maksymmalyhin

FirebaseDatabase/Sources/third_party/SocketRocket/FSRWebSocket.m

@@ -1560,22 +1560,20 @@ - (void)safeHandleEvent:(NSStreamEvent)eventCode stream:(NSStream *)aStream
         case NSStreamEventHasBytesAvailable: {
             SRFastLog(@"NSStreamEventHasBytesAvailable %@", aStream);
 
-            #pragma clang diagnostic push
-            #pragma clang diagnostic ignored "-Wvla"
-            const NSUInteger bufferSize = 2048;
-            uint8_t buffer[bufferSize];
-            #pragma clang diagnostic pop
+            #define FSRWEB_SOCKET_BUFFER_SIZE 2048
+            uint8_t buffer[FSRWEB_SOCKET_BUFFER_SIZE];
+
 
             while (_inputStream.hasBytesAvailable) {
-                NSInteger bytes_read = [_inputStream read:buffer maxLength:bufferSize];
+                NSInteger bytes_read = [_inputStream read:buffer maxLength:FSRWEB_SOCKET_BUFFER_SIZE];
 
                 if (bytes_read > 0) {
                     [_readBuffer appendBytes:buffer length:bytes_read];
                 } else if (bytes_read < 0) {
                     [self _failWithError:_inputStream.streamError];
                 }
 
-                if (bytes_read != bufferSize) {
+                if (bytes_read != FSRWEB_SOCKET_BUFFER_SIZE) {
                     break;
                 }
             };