[moblab] Retrieve correct autodir.

Some tests install autotest in a temporary directory, set the autodir
variable and delete the directory at the end of the test. Previously
moblab_host returning the assigned client directory but now will
return the set autodir variable if it was assigned.

BUG=chromium:410956
TEST=local run of platform_memCheck that requires the cleanup-reboot
dependency.

Change-Id: Ifb9dae233832db75086c168f5f1c260de6b015ec
Reviewed-on: https://chromium-review.googlesource.com/216529
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
1 file changed