Add required network libs for VxWorks

It is needed for proper inet socket address working
on this platform.

Task-number: QTBUG-115777
Change-Id: Icde7ff7baf257762339f5f72a783c92f6b297a46
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 09a21c7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

tests/auto/network/kernel/qhostaddress/tst_qhostaddress.cpp

@@ -15,7 +15,7 @@
 #  include <qt_windows.h>
 #endif
 
-#if defined(Q_OS_ANDROID) || defined(Q_OS_WASM)
+#if defined(Q_OS_ANDROID) || defined(Q_OS_WASM) || defined(Q_OS_VXWORKS)
 #  include <netinet/in.h>
 #endif