calling project.sdk_directory no longer creates the directory
calling project.sdk_directory no longer creates the directory

This lead to build dirs being created everyewhere now
that path.conf contains every sdk dir of the worktree

Change-Id: Ic2bfe2c7fb24e638588e6169dee23c743aa16db8

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