collie: remove a compiler warning

This patch removes a compiler warning in collie_exec_req(). This
warning is produced in the commit 5940548f4, and fixed in
70a4662caa. The latter commit cannot be backported to stable-0.6
because it is a part of the big sockfd moving. This patch manually
removes the warning.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
sheep: correct a way of freeing sockfd_cache_entry

This patch does the same fix done in the commit 44abf0b8. Below is the
commit message of the commit.

  Previous implementation of the sockfd caching mechanism has two memory
  leaks. The leak is caused when sockfd_cache_destroy(),
  sockfd_cache_add_nolock() try to free a sockfd cache entry. They
  forget to free entry->fds.

  This patch adds a new function, free_cache_entry() for safe freeing of
  sockfd cache entries. And let the above two functions to use it.

  Also this patch lets sockfd_cache_add() use free_cache_entry() for
  consistency.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>