libxl: don't end job for ephemeal domain on start failure

commit 4b53d0d4 "libxl: don't remove persistent domain on start
failure" cleans up the vm object and sets it to NULL if the vm is not
persistent, however at end job vm (now NULL) is dereferenced via the call to
libxlDomainObjEndJob. Avoid this by skipping "endjob" and going
straight to "cleanup" in this case.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
(cherry picked from commit ee7758f0)

src/libxl/libxl_driver.c

@@ -992,6 +992,7 @@ libxlDomainCreateXML(virConnectPtr conn, const char *xml,
         if (!vm->persistent) {
             virDomainObjListRemove(driver->domains, vm);
             vm = NULL;
+            goto cleanup;
         }
         goto endjob;
     }