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/libs/utils/fileutils.h

@@ -175,7 +175,6 @@ public:
     using QString::isNull;
     using QString::clear;
 private:
-    static const Qt::CaseSensitivity cs;
     FileName(const QString &string);
 };