Ensure that linux-headers-virtual is installed.

Also linux-headers-`uname -r`.  This is needed for the
stable/diablo branch.  And since apt-get doesn't know how to pull
down the running version, dkms builds can fail if this isn't
installed for the specific running version beforehand.  The
unversioned package will install the lastest version, but that
may not be the kernel the image is currently running.

Change-Id: Idb619ed57f6e101001fea3825c328b471d97e092

devstack-vm-gate-host.sh

@@ -34,6 +34,9 @@ if [ ! -w $DEST ]; then
     sudo chown `whoami` $DEST
 fi
 
+# Make sure headers for the currently running kernel are installed:
+sudo apt-get install -y --force-yes linux-headers-`uname -r`
+
 # Hpcloud provides no swap, but does have a partition mounted at /mnt 
 # we can use:
 if [ `cat /proc/meminfo | grep SwapTotal | awk '{ print $2; }'` -eq 0 ] &&

devstack-vm-update-image.py

@@ -153,7 +153,7 @@ def configure_server(server, branches):
     client = SSHClient(utils.get_public_ip(server), 'jenkins')
     client.ssh('make file cache directory', 'mkdir -p ~/cache/files')
     client.ssh('make pip cache directory', 'mkdir -p ~/cache/pip')
-    client.ssh('install build-essential', 'sudo apt-get install -y --force-yes build-essential python-dev')
+    client.ssh('install build-essential', 'sudo apt-get install -y --force-yes build-essential python-dev linux-headers-virtual linux-headers-`uname -r`')
 
     for branch_data in branches:
         client.ssh('cache debs for branch %s' % branch_data['name'],