clammit: use "exec" in wrapper script

As a good practice, to make sure the exit code is the code of the
wrapped service

software/clammit/buildout.hash.cfg

@@ -15,7 +15,7 @@
 
 [instance.cfg.in]
 filename = instance.cfg.in
-md5sum = 3829d4c7117ffce8bb94aad1e028edb6
+md5sum = da846d59eb75a82d0d392c396517e76d
 
 [clamd.conf.in]
 filename = clamd.conf.in

software/clammit/instance.cfg.in

@@ -121,7 +121,7 @@ output = ${directory:bin}/freshclam
 inline =
   #!/bin/sh
   if [ ! -f "${directory:var.clamdb}/freshclam.dat" ]; then
-    {{ clamav.location }}/bin/freshclam --config-file ${freshclam.conf:output}
+    exec {{ clamav.location }}/bin/freshclam --config-file ${freshclam.conf:output}
   fi
 mode = 700