tst_qdir: optimize setPath() test

On Linux "../" is /tmp, which is more likely to cause issues with the
dir.entrylist() below used in that test; /tmp could have a lot of
temporary files, any of them can be gone in a jiffy. Noticed this test
occasionally falking out when running tests in parallel (`ctest -R
"foo|bar" -j3`).

This may be an unintentional side effect of
b3e9e80719, which changed the code to use
a temporary dir for testing instead of creating/deleting dirs in the
source dir ("../" from the source dir has a more stable entries count
than /tmp).

Change-Id: I98da86223792bc9f34c173fc02cc84049ed699ae
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

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

@@ -341,6 +341,7 @@ void tst_QDir::setPath()
     QFETCH(QString, dir1);
     QFETCH(QString, dir2);
 
+    QDir::setCurrent(m_dataPath + "/entrylist"_L1);
     QDir shared;
     QDir qDir1(dir1);
     QStringList entries1 = qDir1.entryList();