Fix loop to determine MSLSA principal name

Fix loop to determine MSLSA principal name

When looping over principals, check the i-th entry instead of
looking at the 0-th entry each time through the loop.  This would
only affect cases when multiple ticket entries were returned from
the LSA, the first one did not have a valid principal name, but
some other one did.  It is expected that all of the returned
ticket entries will always have a valid client principal name, so
this is unlikely to cause any functional difference.

ticket: 8177 (new)
queue: kfw
tags: pullup
target_version: 1.13.3