Add the sbins to PATH

On fedora (and possibly other systems) sshd is compiled with
--with-default-path=/usr/local/bin:/usr/bin
for non interactive shells because /etc/profile isn't read this
results in PATH not including sbin.

For simplicity I append sbin to the current PATH regardless if it
already exists or not.

Change-Id: I5f6aecb2b1fa9c49f4d15c5d96c005607b05c803

devstack-vm-gate-wrap.sh

@@ -85,6 +85,9 @@ export BASE=/opt/stack
 # The URL from which to fetch ZUUL references
 export ZUUL_URL=${ZUUL_URL:-http://zuul.openstack.org/p}
 
+# sshd may have been compiled with a default path excluding */sbin
+export PATH=$PATH:/usr/local/sbin:/usr/sbin
+
 # Set this variable to skip updating the devstack-gate project itself.
 # Useful in development so you can edit scripts in place and run them
 # directly.  Do not set in production.