licenses: add 0BSD

In spite of its name this is not related to the BSD license but is
effectively a public domain dedication. It originated with toybox. It is
OSI approved and has an SPDX identifier of "0BSD".

https://opensource.org/licenses/0BSD
https://fedoraproject.org/wiki/Licensing/ZeroClauseBSD

Gentoo originally added it in this commit:
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=569bd63cd13445d8cd3abd2fe0198c5a2523842f
and tweaked the text in this commit:
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=3f1f74ddd6e45e07827fe571c6f41b4b1225857e

BUG=b:200509009
TEST=repo upload . # in chromiumos-overlay with changes to dev-rust/spi-memory

Change-Id: I0458c57b8ded7755ea6fb1d6904e06224edf3c32
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3168424
Tested-by: Dan Callaghan <dcallagh@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Dan Callaghan <dcallagh@chromium.org>
diff --git a/licenses/0BSD b/licenses/0BSD
new file mode 100644
index 0000000..17a43d8
--- /dev/null
+++ b/licenses/0BSD
@@ -0,0 +1,12 @@
+Copyright (C) <years> by <copyright holder>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.