apply: handle type-changing patch correctly.

apply: handle type-changing patch correctly.

A type-change diff is always split into a patch to delete old,
immediately followed by a patch to create new.  check_patch()
routine noticed that the path to be created already exists in
the working tree and/or in the index when looking at the
creation patch and mistakenly thought it to be an error.

Signed-off-by: Junio C Hamano <redacted>