Check mech in gss_accept_sec_context w/ no cred

If no verifier_cred_handle is passed to gss_accept_sec_context(),
accept the same mechs as we would with a default acceptor
credential--that is, not those which assert the GSS_C_MA_DEPRECATED or
GSS_C_MA_NOT_DFLT_MECH attributes.

https://github.com/krb5/krb5/commit/382556f580e3b7fb8469976988c50b67bba51f26
Author: Greg Hudson <ghudson@mit.edu>
Commit: 382556f580e3b7fb8469976988c50b67bba51f26
Branch: master
 src/lib/gssapi/mechglue/g_accept_sec_context.c |   28 ++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)