Fix kadm5.acl error reporting

Fix kadm5.acl error reporting

In kadm5int_acl_get_line(), increment *lnp after skipping a blank or
comment line, so that kadm5int_acl_load_acl_file() correctly reports
the line number if it fails to parse a line.

In acl_syn_err_msg, use %.10s to limit the amount of the line included
in the error message, not %10s to left-pad it with spaces if it is
shorter than ten characters.

ticket: 8588 (new)
target_version: 1.15-next
target_version: 1.14-next
tags: pullup