Fix cmake bug when trying to compare _SUBFOLDER and ""
Fix cmake bug when trying to compare _SUBFOLDER and ""

Change-Id: I15ffe751624f66b47d78f80157e29e945e5b37e3

aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild