krb5 releases 1.18 and later completely remove support for
all DES3 enctypes (des3-cbc-raw, des3-hmac-sha1, des3-cbc-sha1-kd).

This patch adds HAVE_DES3_SUPPORT to check if DES3 enctype
is supported.

Change-Id: Ibb51ec7961e8c775ea92dec6119f4de01e2d9b1d
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/40560


Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>