Recognize QNX and define __QNX__ under it. Don't use -lpthreads as the thread functions are in libc under QNX. Use wxX11 by default. See #11790. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63664 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775