commonlib: Add commonlib/bsd

This patch creates a new commonlib/bsd subdirectory with a similar
purpose to the existing commonlib, with the difference that all files
under this subdirectory shall be licensed under the BSD-3-Clause license
(or compatible permissive license). The goal is to allow more code to be
shared with libpayload in the future.

Initially, I'm going to move a few files there that have already been
BSD-licensed in the existing commonlib. I am also exracting most
contents of the often-needed <commonlib/helpers.h> as long as they have
either been written by me (and are hereby relicensed) or have an
existing equivalent in BSD-licensed libpayload code. I am also
relicensing <commonlib/compression.h> (written by me) and
<commonlib/compiler.h> (same stuff exists in libpayload).

Finally, I am extracting the cb_err error code definitions from
<types.h> into a new BSD-licensed header so that future commonlib/bsd
code can build upon a common set of error values. I am making the
assumption here that the enum constants and the half-sentence fragments
of documentation next to them by themselves do not meet the threshold of
copyrightability.

Change-Id: I316cea70930f131e8e93d4218542ddb5ae4b63a2
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38420
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/lib/selfboot.c

@@ -15,7 +15,7 @@
  * GNU General Public License for more details.
  */
 
-#include <commonlib/compression.h>
+#include <commonlib/bsd/compression.h>
 #include <commonlib/endian.h>
 #include <console/console.h>
 #include <stdint.h>