Check for crypt in external library

Check for crypt in external library

Check to see if we need to explicitly include a library in order
to get the crypt() function

Change-Id: I9bd1d70e420d4d1656bd86cd3215525102fa6259
Reviewed-on: http://gerrit.openafs.org/2404
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit c3fc948e34ad6c44df88e77e5a00e7d3119f627e)