HostOsInfo: Add some more useful abstractions.

Namely:
- path list separator
- executable suffix
- file name case sensitivity

All of these are duplicated in various places in the current Creator
code.

Change-Id: I86eb4662fa3c2071759bd728cae1aaf7111ae686
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/plugins/qt4projectmanager/qt4nodes.cpp

@@ -2270,8 +2270,7 @@ TargetInformation Qt4ProFileNode::targetInformation(QtSupport::ProFileReader *re
     result.executable = QDir::cleanPath(wd + QLatin1Char('/') + result.target);
     //qDebug() << "##### updateTarget sets:" << result.workingDir << result.executable;
 
-    if (Utils::HostOsInfo::isWindowsHost())
-        result.executable += QLatin1String(".exe");
+    Utils::HostOsInfo::appendExecutableSuffix(result.executable);
     result.valid = true;
     return result;
 }