Update reachover build files for atf-0.20.

Adjust for import of atf 0.19.

- Delete some unnecessary files.
- Print out both the list of deleted files and added files in the import.
Useful when adjusting file lists and the reachover Makefiles.

branches: 1.6.6;
Update reachover build files and scripts to deal with the just-imported
atf 0.15.

branches: 1.5.2;
Update reachover build files for atf-0.14.

branches: 1.4.2;
Adjust reachover build files with the import of atf-0.13.

Sync list of files to ignore in preparation for the 0.11 import.

Update reachover makefiles for atf 0.10.

Add a script to help with the import of new atf releases: it extracts a
distfile, places it in dist and cleans up any unnecessary files.

Catchup with rmind-uvmplock merge.

sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")

sync with head

Rebase to HEAD as of a few days ago.