make sure qmake finds itself in CWD on windows

and consequently that it finds qt.conf.

Task-number: QTBUG-30583
Change-Id: I48441477e941d9609270d6e5e1b405127c0c0aca
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

qmake/option.cpp

@@ -338,6 +338,7 @@ Option::init(int argc, char **argv)
             QDir currentDir = QDir::current();
 #ifdef Q_OS_WIN
             QStringList paths = QString::fromLocal8Bit(pEnv).split(QLatin1String(";"));
+            paths.prepend(QLatin1String("."));
 #else
             QStringList paths = QString::fromLocal8Bit(pEnv).split(QLatin1String(":"));
 #endif