mirror.starlingx.cengn.ca no longer exists. CENGN is kindly forwarding
requests to the new location mirror.starlingx.windriver.com for now, but
that will only last a few months. We need to replace all the references
with the new URL.
I will also remove as many 'cengn' references as possible, replacing
them with 'stx_mirror'
Partial-Bug: 2033555
Signed-off-by: Scott Little <scott.little@windriver.com>
Change-Id: I09e3f564edef2049786c965a86dbcaacac359801
6f3d1e5dd2