Utils: Add FilePath::isSymLink

Needed to fix GenericUploadStep handle the device->device case.

Change-Id: I551ac0957879e5b8737c22fa823d8b2e6bec0b5e
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/filepath.h

@@ -107,6 +107,7 @@ public:
     bool isAbsolutePath() const { return !isRelativePath(); }
     bool isFile() const;
     bool isDir() const;
+    bool isSymLink() const;
     bool isRootPath() const;
     bool isNewerThan(const QDateTime &timeStamp) const;
     QDateTime lastModified() const;