Minor optimizations

Ran the clazy tool (http://www.kdab.com/use-static-analysis-improve-performance/)

Mostly QStringLiteral/QLatin1String additions
A few const & additions to non public methods

Compiles, test pass

REVIEW: 125106

1 files changed, 1 insertions, 1 deletions

diff --git a/src/core/kconfigbackend.cpp b/src/core/kconfigbackend.cpp
index 67bdefa4..16bcf0fe 100644
--- a/src/core/kconfigbackend.cpp
+++ b/src/core/kconfigbackend.cpp
@@ -44,7 +44,7 @@ public:
 
     static QString whatSystem(const QString & /*fileName*/)
     {
-        return QLatin1String("INI");
+        return QStringLiteral("INI");
     }
 };