Add linux-readline target support for 5.4.x

[Kazuo256]

According to Lua 5.4.x's README:

If you're running Linux, try "make linux-readline" to build the interactive Lua interpreter with handy line-editing and history capabilities.

Not a very good bash scripter, so maybe this is not the best approach.

[umireon]

This project won't permit bashisms.

[Kazuo256]

I'm not familiar with the expression "bashisms". What does it mean?

[umireon]

This works with bash but does not work with POSIX sh. This is called bashisms.

[[ "${version}" =~ 5[.]4[.][0-9]+ ]]

You can detect them by ShellCheck.

$ shellcheck -s sh -e SC2039 luaver
 
Line 2:
[[ "${version}" =~ 5[.]4[.][0-9]+ ]]
^-- SC3010: In POSIX sh, [[ ]] is undefined.

You can use awk.

[ -n "$('echo' "${version}" | 'awk' '/^5\.4\./')" ]

[Kazuo256]

Sorry for the long delay, I somehow didn't receive any notifications for the reply.

I changed the PR to use the code you suggested. Testing locally, it seems to work.