lock_file: better message if too many open files

[scpeters]

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I ran into the same issue reported in #11530 (somehow my ulimit -n was only 256), but I found the error message a bit confusing, and it took me a while to find the recommendation to adjust ulimit -n. I've added a rescue Errno::EMFILE around the offending call in lock_file.rb and added an onoe message that recommends using ulimit -n to increase the maximum number of open files.

$ brew upgrade osrf/simulation/gz-sim7 --debug
...
==> Upgrading osrf/simulation/gz-sim7
  7.3.0 -> 7.4.0 

Error: Consider using `ulimit -n` to increase the maximum number of open files allowed on this system.
Error: Too many open files @ rb_sysopen - /usr/local/var/homebrew/locks/gz-physics6.formula.lock
/usr/local/Homebrew/Library/Homebrew/lock_file.rb:46:in `initialize'
/usr/local/Homebrew/Library/Homebrew/lock_file.rb:46:in `open'
/usr/local/Homebrew/Library/Homebrew/lock_file.rb:46:in `open'
/usr/local/Homebrew/Library/Homebrew/lock_file.rb:46:in `create_lockfile'
/usr/local/Homebrew/Library/Homebrew/lock_file.rb:20:in `lock'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1352:in `lock'
/usr/local/Homebrew/Library/Homebrew/formula_installer.rb:1293:in `each'
/usr/local/Homebrew/Library/Homebrew/formula_installer.rb:1293:in `lock'
/usr/local/Homebrew/Library/Homebrew/formula_installer.rb:376:in `install'
/usr/local/Homebrew/Library/Homebrew/upgrade.rb:203:in `install_formula'
/usr/local/Homebrew/Library/Homebrew/upgrade.rb:176:in `upgrade_formula'
/usr/local/Homebrew/Library/Homebrew/upgrade.rb:86:in `block in upgrade_formulae'
/usr/local/Homebrew/Library/Homebrew/upgrade.rb:85:in `each'
/usr/local/Homebrew/Library/Homebrew/upgrade.rb:85:in `upgrade_formulae'
/usr/local/Homebrew/Library/Homebrew/cmd/upgrade.rb:194:in `upgrade_outdated_formulae'
/usr/local/Homebrew/Library/Homebrew/cmd/upgrade.rb:116:in `upgrade'
/usr/local/Homebrew/Library/Homebrew/brew.rb:93:in `<main>'

[BrewTestBot]

Review period will end on 2023-03-07 at 00:00:00 UTC.

[apainintheneck]

Makes sense to me.

[BrewTestBot]

Review period ended.

[MikeMcQuaid]

Thanks again @scpeters!