Add KRB5_PRINCIPAL_PARSE_NO_DEF_REALM flag

Implement KRB5_PRINCIPAL_PARSE_NO_DEF_REALM from Heimdal.  This flag
for krb5_parse_name_flags() suppresses the addition of the default
realm, but allows and preserves the realm if one is specified in the
string.

https://github.com/krb5/krb5/commit/5975ab86bf0ab791282cf1103b8143cccd1034fd
Author: Greg Hudson <ghudson@mit.edu>
Commit: 5975ab86bf0ab791282cf1103b8143cccd1034fd
Branch: master
 src/include/krb5/krb5.hin |    1 +
 src/lib/krb5/krb/parse.c  |   10 ++++------
 2 files changed, 5 insertions(+), 6 deletions(-)