CVE-2015-6563

Don't resend username to PAM; it already has it. 
Pointed out by Moritz Jodeit; ok dtucker@

Upstream-Status: Backport
https://github.com/openssh/openssh-portable/commit/d4697fe9a28dab7255c60433e4dd23cf7fce8a8b

Signed-off-by: Armin Kuster <akuster@mvista.com>

Index: openssh-6.7p1/monitor.c
===================================================================
--- openssh-6.7p1.orig/monitor.c
+++ openssh-6.7p1/monitor.c
@@ -1046,9 +1046,7 @@ extern KbdintDevice sshpam_device;
 int
 mm_answer_pam_init_ctx(int sock, Buffer *m)
 {
-
 	debug3("%s", __func__);
-	authctxt->user = buffer_get_string(m, NULL);
 	sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
 	sshpam_authok = NULL;
 	buffer_clear(m);
Index: openssh-6.7p1/monitor_wrap.c
===================================================================
--- openssh-6.7p1.orig/monitor_wrap.c
+++ openssh-6.7p1/monitor_wrap.c
@@ -826,7 +826,6 @@ mm_sshpam_init_ctx(Authctxt *authctxt)
 
 	debug3("%s", __func__);
 	buffer_init(&m);
-	buffer_put_cstring(&m, authctxt->user);
 	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_INIT_CTX, &m);
 	debug3("%s: waiting for MONITOR_ANS_PAM_INIT_CTX", __func__);
 	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PAM_INIT_CTX, &m);