Read qmldir files in a thread and cache them in Snapshot.

Reviewed-by: Erik Verbruggen

src/libs/qmljs/parser/gen-parser.sh

@@ -10,3 +10,5 @@ for i in $QTDIR/src/declarative/qml/qdeclarative{error.{h,cpp},dirparser{_p.h,.c
     sed -f $me/cmd.sed $i > $me/$(echo $(basename $i) | sed s/qdeclarative/qml/)
 done
 
+# export QmlDirParser
+perl -p -0777 -i -e 's/QT_BEGIN_NAMESPACE\n\nclass QmlError;\n\nclass QmlDirParser/#include "qmljsglobal_p.h"\n\nQT_BEGIN_NAMESPACE\n\nclass QmlError;\n\nclass QML_PARSER_EXPORT QmlDirParser/' qmldirparser_p.h