Remove unnecessary VxWorks ifdef

Change-Id: Ie655bdff9a09c6060f66e4346b94ba52443241f4
Reviewed-by: Tuomas Heimonen <tuomas.heimonen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/auto/corelib/io/qdir/tst_qdir.cpp

@@ -1662,9 +1662,7 @@ void tst_QDir::homePath()
         QVERIFY(!strHome.endsWith('/'));
 
     QByteArray envHome = qgetenv("HOME");
-#if !defined(_WRS_KERNEL) // unsetenv is not available on VxWorks DKM mode
     unsetenv("HOME");
-#endif
     QCOMPARE(QDir::homePath(), QDir::rootPath());
     qputenv("HOME", envHome);