Fix condition with empty body

Found by clang's warnings.

(cherry picked from commit 18796a2eb6c05706c6635453b3e425955aab93f4)

https://github.com/krb5/krb5/commit/63b5902e83eb7d47f2eb061acde2566ec1d45bc8
Author: David Benjamin <davidben@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 63b5902e83eb7d47f2eb061acde2566ec1d45bc8
Branch: krb5-1.10
 src/lib/kdb/keytab.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)