Add llvmfuzz and oss-fuzz integration, fixed many minor fuzzing errors. libfuzzer is much better than afl++ and honggfuzz.

See https://www.gnu.org/software/libredwg/ and NEWS

Here are the compressed sources:
http://ftp.gnu.org/gnu/libredwg/libredwg-0.12.3.tar.gz (17.4MB)
http://ftp.gnu.org/gnu/libredwg/libredwg-0.12.3.tar.xz (9MB)

Here are the GPG detached signatures[*]:
http://ftp.gnu.org/gnu/libredwg/libredwg-0.12.3.tar.gz.sig
http://ftp.gnu.org/gnu/libredwg/libredwg-0.12.3.tar.xz.sig

Use a mirror for higher download bandwidth:
https://www.gnu.org/order/ftp.html

Here are more binaries:
https://github.com/LibreDWG/libredwg/releases/tag/0.12.3

Here are the SHA256 checksums:

47933ccc0230c66c571606f7a5897fa1fb0f664fba871b883f1a785783f58a33  libredwg-0.12.3.tar.gz
b31a33466ba23312119138d0ac022399841ee0f40d9bbd970410a2fc471e15ee  libredwg-0.12.3.tar.xz
8eb64bb281afd718ab15d5868f58a74a8a37a71051a20a843e2ec1d936c69d4e  libredwg-0.12.3-win64.zip
d947868fae79bcff91832c188efa89e508840ac64e1708acba0f69e500c97bd6  libredwg-0.12.3-win32.zip

[*] Use a .sig file to verify that the corresponding file (without the
.sig suffix) is intact. First, be sure to download both the .sig file
and the corresponding tarball. Then, run a command like this:

gpg --verify libredwg-0.12.3.tar.gz.sig

If that command fails because you don't have the required public key,
then run this command to import it:

gpg --keyserver keys.gnupg.net --recv-keys B4F63339E65D6414

and rerun the gpg --verify command.