Better solution for 64->32 bit narrowing.

kmdewaal suggested a better solution for this cast that doesn't
require any conditional compilation.

mythtv/libs/libmythtv/recorders/dvbchannel.cpp

@@ -1589,12 +1589,9 @@ bool DVBChannel::WaitForBackend(std::chrono::milliseconds timeout_ms)
     const int fd  = m_fdFrontend;
     auto seconds = duration_cast<std::chrono::seconds>(timeout_ms);
     auto usecs = duration_cast<std::chrono::microseconds>(timeout_ms) - seconds;
-#if defined(__x86_64__)
-    struct timeval select_timeout = { seconds.count(), usecs.count()};
-#else
-    struct timeval select_timeout = { static_cast<int32_t>(seconds.count()),
-                                      static_cast<int32_t>(usecs.count()) };
-#endif
+    struct timeval select_timeout = {
+         static_cast<typeof(select_timeout.tv_sec)>(seconds.count()),
+         static_cast<typeof(select_timeout.tv_usec)>(usecs.count())};
     fd_set fd_select_set;
     FD_ZERO(    &fd_select_set); // NOLINT(readability-isolate-declaration)
     FD_SET (fd, &fd_select_set);