Fix a pair of non-ascii quotes that made their way into AsyncSocket

Summary: Because the lint error was annoying me.

Reviewed By: yfeldblum

Differential Revision: D3671252

fbshipit-source-id: 2962db7616077f531e64c6f2b26ad708c7adf6ed

folly/io/async/AsyncSocket.cpp

@@ -663,8 +663,7 @@ void AsyncSocket::writeChain(WriteCallback* callback, unique_ptr<IOBuf>&& buf,
   constexpr size_t kSmallSizeMax = 64;
   size_t count = buf->countChainElements();
   if (count <= kSmallSizeMax) {
-
-    // suppress "warning: variable length array ‘vec’ is used [-Wvla]"
+    // suppress "warning: variable length array 'vec' is used [-Wvla]"
     FOLLY_PUSH_WARNING;
     FOLLY_GCC_DISABLE_WARNING(vla);
     iovec vec[BOOST_PP_IF(FOLLY_HAVE_VLA, count, kSmallSizeMax)];