CTF: Use qEnvironmentVariable

Pick-to: 6.5
Change-Id: I492da6862491cc476355a318652bd9901fffcd76
Reviewed-by: Janne Koskinen <janne.p.koskinen@qt.io>
Reviewed-by: Hatem ElKharashy <hatem.elkharashy@qt.io>

src/plugins/tracing/qctflib.cpp

@@ -56,7 +56,7 @@ void QCtfLibImpl::cleanup()
 
 QCtfLibImpl::QCtfLibImpl()
 {
-    QString location = QString::fromUtf8(qgetenv("QTRACE_LOCATION"));
+    QString location = qEnvironmentVariable("QTRACE_LOCATION");
     if (location.isEmpty()) {
         qCInfo (lcDebugTrace) << "QTRACE_LOCATION not set";
         return;