Move everything into a separate futatabi/ subdir, for the upcoming merge with Futatabi.

[nageru] / bmusb

diff --git a/bmusb b/bmusb
index e9aa80b8e6a09cf2c8b3458a1c395b6f1b6a58cc..5163d25c65c3028090db1aea6587ec2fb4cb823e 160000 (submodule)
--- a/bmusb
+++ b/bmusb
@@ -1 +1 @@
-Subproject commit e9aa80b8e6a09cf2c8b3458a1c395b6f1b6a58cc
+Subproject commit 5163d25c65c3028090db1aea6587ec2fb4cb823e