tree-wide: Remove unused variables detected by CLang

CLang finds these, whereas GCC treats having
`__attribute__((cleanup))` as a use.

This obsoletes https://github.com/ostreedev/ostree/pull/411

Closes: #548
Approved by: jlebon

src/libostree/ostree-sysroot-deploy.c

@@ -534,7 +534,6 @@ checkout_deployment_tree (OstreeSysroot     *sysroot,
   const char *csum = ostree_deployment_get_csum (deployment);
   g_autofree char *checkout_target_name = NULL;
   g_autofree char *osdeploy_path = NULL;
-  g_autoptr(GFile) ret_deploy_target_path = NULL;
   glnx_fd_close int osdeploy_dfd = -1;
   int ret_fd;
 
@@ -1199,7 +1198,6 @@ swap_bootlinks (OstreeSysroot *self,
   gboolean ret = FALSE;
   int old_subbootversion, new_subbootversion;
   glnx_fd_close int ostree_dfd = -1;
-  glnx_fd_close int ostree_subbootdir_dfd = -1;
   g_autofree char *ostree_bootdir_name = NULL;
   g_autofree char *ostree_subbootdir_name = NULL;