Core: Fix build

Amends 104ea4accc.

Change-Id: I2688962c5b5c99c31324fa6eb94aa9ae28665266
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/coreplugin/icontext.cpp

@@ -27,6 +27,7 @@
 
 #include <QDebug>
 
+namespace Core {
 QDebug operator<<(QDebug debug, const Core::Context &context)
 {
     debug.nospace() << "Context(";
@@ -44,6 +45,7 @@ QDebug operator<<(QDebug debug, const Core::Context &context)
 
     return debug;
 }
+} // namespace Core
 
 /*!
     \class Core::Context