[krbdev.mit.edu #2284] Replay cache not used in GSS_C_NO_CREDENTIAL case

[Tom Yu via RT]

More precisely, the explicit setting of KRB5_AUTH_CONTEXT_DO_SEQUENCE
by accept_sec_context() prior to its call of krb5_rd_req() prevents
krb5_rd_req() from setting up the temporary rcache.  Setting the flag
clears the default flag KRB5_AUTH_CONTEXT_DO_TIME, which krb5_rd_req()
checks to determine whether to set up a temporary rcache.