QmlJS: Fix compile

..in general, with tests, and when using a namespaced Qt.
Amends b09a48599e.

Change-Id: I99e275e10df5eed741d021911a360457f0d0d2e7
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/libs/qmljs/parser/qmljslexer.cpp

@@ -36,8 +36,9 @@
 #include <QtCore/QScopedValueRollback>
 
 QT_QML_BEGIN_NAMESPACE
+QT_BEGIN_NAMESPACE
 Q_CORE_EXPORT double qstrtod(const char *s00, char const **se, bool *ok);
-QT_QML_END_NAMESPACE
+QT_END_NAMESPACE
 
 using namespace QmlJS;
 
@@ -1619,3 +1620,5 @@ bool Lexer::scanDirectives(Directives *directives, DiagnosticMessage *error)
 
     return true;
 }
+
+QT_QML_END_NAMESPACE