aarch64 doesn't have SYS_futimesat

we picked something obscure, and clearly aarch64 took advantage of
not adding something obscure unnecessary for backwards compatibility
on that arch

Signed-off-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Change-Id: I097ef24c98e23931a3997c743d17d52c0afd52b7

net/Socket.cpp

@@ -1501,7 +1501,7 @@ namespace http
 extern "C" {
     void handleUserProfileSignal(const int /* signal */)
     {
-#if defined(__linux__) && !defined(__ANDROID__)
+#if defined(__linux__) && !defined(__ANDROID__) && defined(SYS_futimesat)
         const struct timeval times[2] = {};
         // call something fairly obscure that perf can trigger on.  futimesat
         // look a good candidate (calling "futimesat" typically results in