We want to use this from multiple extensions so let's move it.
- Group Reviewers
- rFBHGX0eb3df0e50c0: extutil: move flock to extutil
This is using flock() instead of fcntl() libc function/syscall (the Python module name "fcntl" is just confusing - flock() has nothing to do with fcntl). The comment needs to be updated to use flock.