wxUSE_GSTREAMER is Unix-specific, remove it from common wx/setup_inc.h; it also requires wxUSE_THREADS, check for it

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60727 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/chkconf.h

@@ -20,3 +20,14 @@
 #       endif
 #   endif
 #endif /* wxUSE_CONSOLE_EVENTLOOP */
+
+#if wxUSE_GSTREAMER
+#   if !wxUSE_THREADS
+#       ifdef wxABORT_ON_CONFIG_ERROR
+#           error "GStreamer requires threads"
+#       else
+#           undef wxUSE_GSTREAMER
+#           define wxUSE_GSTREAMER 0
+#       endif
+#   endif
+#endif /* wxUSE_GSTREAMER */