Compilation fix of wxSocket code for older Solaris versions.

Include sys/filio.h to define FIONBIO in all cases (sometimes this header is
already included from sys/ioctl.h but not always).

Closes #12481.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65581 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/private/sockunix.h

@@ -14,6 +14,14 @@
 
 #include <unistd.h>
 #include <sys/ioctl.h>
+
+// Under older (Open)Solaris versions FIONBIO is declared in this header only.
+// In the newer versions it's included by sys/ioctl.h but it's simpler to just
+// include it always instead of testing for whether it is or not.
+#ifdef __SOLARIS__
+    #include <sys/filio.h>
+#endif
+
 #include "wx/private/fdiomanager.h"
 
 class wxSocketImplUnix : public wxSocketImpl,