CppCheck: Tr::tr and code cosmetics

Change-Id: I5e6583984f7dc94e998df3c20840f2ba2e801ab8
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/cppcheck/cppchecktool.h

@@ -14,18 +14,13 @@
 namespace Utils {
 class FilePath;
 using FilePaths = QList<FilePath>;
-}
+} // Utils
 
-namespace CppEditor {
-class ProjectPart;
-}
+namespace CppEditor { class ProjectPart; }
 
-namespace ProjectExplorer {
-class Project;
-}
+namespace ProjectExplorer { class Project; }
 
-namespace Cppcheck {
-namespace Internal {
+namespace Cppcheck::Internal {
 
 class CppcheckRunner;
 class CppcheckDiagnosticManager;
@@ -68,5 +63,4 @@ private:
     Utils::Id m_progressId;
 };
 
-} // namespace Internal
-} // namespace Cppcheck
+} // Cppcheck::Internal