Ignore compiled unit test executables
Clean up copyright notifications and license statements

Collect all copyright and license statements into LICENSE file.
Individual file headers were out of date, and this is better than
maintaining them spread out over the code base. Per-file copyright
headers are from an era where people would routinely print out
individual files, and when software was distributed as tarballs with
no history; let's move on. If information about specific years of
authorship for a particular file are needed, the version control
system will act as historical record.

Also take care to note the few files with a longer history. The
fuse_kernel.h derivation is merely a question of this software using a
public interface defined by that file, I do not personally believe
that the original work has creative value in it. The two files adapted
from 9pfuse are true derived works, but their licenses are very free
and should pose no problem.

The main license itself seems to be written by the Google lawyers, and
is a variation of the well-known 2-clause BSD license, with a single
word substitution: "copyright holder" has been changed to "copyright
owner".
Add a README file