merge-recursive: Nuke rename/directory conflict detection

merge-recursive: Nuke rename/directory conflict detection

Since we want to resolve merges in-core and then detect at the end whether
D/F conflicts remain in the way, we should just apply renames in-core and
let logic elsewhere check for D/F conflicts.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>