upstream: Add TEST_SSH_SSHD_ENV variable which is added to sshd's

environment. Will be used in Portable to tweak behaviour of tcmalloc's
debugging.

OpenBSD-Regress-ID: 67e38c3c4517ddb72c8a3549a3325a166d7bb6d6

Author: daztucker

regress/test-exec.sh

@@ -1,4 +1,4 @@
-#	$OpenBSD: test-exec.sh,v 1.125 2025/03/28 05:33:30 dtucker Exp $
+#	$OpenBSD: test-exec.sh,v 1.126 2025/03/28 05:36:24 dtucker Exp $
 #	Placed in the Public Domain.
 
 #SUDO=sudo
@@ -884,7 +884,7 @@ fi
 # create a proxy version of the client config
 (
 	cat $OBJ/ssh_config
-	echo proxycommand ${SUDO} env SSH_SK_HELPER=\"$SSH_SK_HELPER\" ${OBJ}/sshd-log-wrapper.sh -i -f $OBJ/sshd_proxy
+	echo proxycommand ${SUDO} env SSH_SK_HELPER=\"$SSH_SK_HELPER\" ${TEST_SSH_SSHD_ENV} ${OBJ}/sshd-log-wrapper.sh -i -f $OBJ/sshd_proxy
 ) > $OBJ/ssh_proxy
 
 # check proxy config
@@ -902,7 +902,7 @@ start_sshd ()
 	# start sshd
 	logfile="${TEST_SSH_LOGDIR}/sshd.`$OBJ/timestamp`.$$.log"
 	$SUDO ${SSHD} -f $OBJ/sshd_config "$@" -t || fatal "sshd_config broken"
-	$SUDO env SSH_SK_HELPER="$SSH_SK_HELPER" \
+	$SUDO env SSH_SK_HELPER="$SSH_SK_HELPER" ${TEST_SSH_SSHD_ENV} \
 	    ${SSHD} -f $OBJ/sshd_config "$@" -E$TEST_SSHD_LOGFILE
 
 	trace "wait for sshd"