Install krb5-config man page

Don't just build it.

(cherry picked from commit 2defbe8939c1c11a9f76334443c63603a8b749bf)

https://github.com/krb5/krb5/commit/050d60471d6608126b174a6c64bd2851386b15ca
Author: Ben Kaduk <kaduk@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 050d60471d6608126b174a6c64bd2851386b15ca
Branch: krb5-1.11
 src/man/Makefile.in |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)