utils/environment: performance

Yes, showed up in callgrind.

Change-Id: Icb4fb9d8ed047eedf66e2e1a4bb2f24b9e217146
Reviewed-on: http://codereview.qt.nokia.com/83
Reviewed-by: hjk

src/libs/utils/environment.cpp

@@ -74,7 +74,7 @@ Environment::Environment()
 Environment::Environment(QStringList env)
 {
     foreach (const QString &s, env) {
-        int i = s.indexOf("=");
+        int i = s.indexOf(QLatin1Char('='));
         if (i >= 0) {
 #ifdef Q_OS_WIN
             m_values.insert(s.left(i).toUpper(), s.mid(i+1));