Fix build when liburing is installed (#1487)

Summary:
Fixes https://github.com/facebook/folly/issues/1486

Pull Request resolved: https://github.com/facebook/folly/pull/1487

Reviewed By: Orvid

Differential Revision: D24851586

Pulled By: yfeldblum

fbshipit-source-id: ae683ba73336c562a8912ed35ef2b3318ab53519

folly/experimental/io/IoUringBackend.cpp

@@ -19,6 +19,7 @@
 #include <folly/String.h>
 #include <folly/container/F14Map.h>
 #include <folly/container/F14Set.h>
+#include <folly/portability/GFlags.h>
 #include <folly/portability/Sockets.h>
 #include <folly/synchronization/CallOnce.h>
 

folly/experimental/io/SimpleAsyncIO.cpp

@@ -25,7 +25,7 @@
 #include <folly/experimental/io/IoUring.h>
 #endif
 
-#if !defined(AIO_SUPPORTED) && !defined(IOURING_SUPORTED)
+#if !defined(AIO_SUPPORTED) && !defined(IOURING_SUPPORTED)
 #error "Cannot build without at least one of AsyncIO.h and IoUring.h"
 #endif