Description of problem:
Can we please include the upstream commit http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=48755ebf093543113de96747a7f5f78e0640b333 (and the dependent factor out one 0541a1adf7c25356e7bbd792a8d6ee217a0d92f3) so that we do not call close() on "max_fd = sysconf(_SC_OPEN_MAX);" which can be quite high depending on host or container (max fd) where it is being run?

Asking because it quite affects startup performance when a container has a largish 1M fds:
A) Pristine rhel-8.2 dnsmasq-2.79-11.el8.x86_64
19    11:26:49.414861 execve("/sbin/dnsmasq", ["/sbin/dnsmasq", "--conf-file=/etc/ironic-inspector/dnsmasq.conf", "-k", "--log-facility=/var/log/ironic-inspector/dnsmasq.log"], 0x7fffd9e40bc8 /* 15 vars */) = 0 
...
19    11:26:49.436593 close(6)          = -1 EBADF (Bad file descriptor)
...
19    11:27:20.776605 close(1048575)    = -1 EBADF (Bad file descriptor)  
...
19    11:27:20.793024 poll([{fd=4<socket:[2140744]>, events=POLLIN}, {fd=5<socket:[2140745]>, events=POLLIN}, {fd=6<anon_inode:inotify>, events=POLLIN}, {fd=7<pipe:[2140751]>, events=POLLIN}], 4, -1 

B) dnsmasq-2.79-11.0.noclose.0.el8.x86_64 which has two patches applied: 
- 0541a1adf7c25356e7bbd792a8d6ee217a0d92f3 Factor out closing all file descriptors for later
- 48755ebf093543113de96747a7f5f78e0640b333 Optimise closing file descriptors.

18    11:29:47.527284 execve("/sbin/dnsmasq", ["/sbin/dnsmasq", "--conf-file=/etc/ironic-inspector/dnsmasq.conf", "-k", "--log-facility=/var/log/ironic-inspector/dnsmasq.log"], 0x7ffe5dbac1e8 /* 15 vars */) = 0
...
18    11:29:47.553800 poll([{fd=4<socket:[2176572]>, events=POLLIN}, {fd=5<socket:[2176573]>, events=POLLIN}, {fd=6<anon_inode:inotify>, events=POLLIN}, {fd=7<pipe:[2176579]>, events=POLLIN}], 4, -1

Now tests were run under strace so clearly exacerbated the slowness of case A), but the point still remains.
We're trying to hunt down all these unneeded close() calls all over OSP (e.g. https://bugzilla.redhat.com/show_bug.cgi?id=1762025, https://github.com/erlang/otp/pull/2438, https://bugzilla.redhat.com/show_bug.cgi?id=1762794 ) and it would be nice if we applied those two upstream commits from dnsmasq as well.