In the past, we allocated a buffer with zeroes and wrote that with
fwrite. Now, instead we just fseek to the correct offset.
This changes the way in which the file extract limit is counted a bit;
skipped bytes do no longer count against the file size limit.
(cherry picked from commit 5071592e9b7105090a1d9de19689c499070749d4)
* All "Broxygen" usages have been replaced in
code, documentation, filenames, etc.
* Sphinx roles/directives like ":bro:see" are now ":zeek:see"
* The "--broxygen" command-line option is now "--zeexygen"
