Check strdup return in kadm5_get_config_params()

When copying the realm string, if strdup() returns NULL, fail out with
ENOMEM instead of pretending the realm wasn't specified.  When copying
KRB5_DEFAULT_SUPPORTED_ENCTYPES, if strdup() returns NULL, fail out
with ENOMEM instead of crashing.  Reported by Bean Zhang.

(cherry picked from commit c0af219be218c02e72160ecd0521bc5b9bad546f)

https://github.com/krb5/krb5/commit/d6ce2d8273bf4b2a51de882866e42d33d1f568ca
Author: Greg Hudson <ghudson@mit.edu>
Commit: d6ce2d8273bf4b2a51de882866e42d33d1f568ca
Branch: krb5-1.15
 src/lib/kadm5/alt_prof.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)