main/luajit: switch to OpenResty's maintained branch

The MoonJIT fork is unmaintained since September 2020 1:

This code base does not have an active maintainer anymore, please read this Twitter thread to know more. If you are an existing contributor (or otherwise have an interest in maintaining this project actively) then please email me using the email address in my Twitter profile.

Moreover, the transition from original LuaJIT to MoonJIT caused multiple compatibility and stability issues, mainly with Lua NGINX module (#12410 (closed), #10478 (closed)), but also with some Lua packages written in C (segfaults).

I wanted to switch back to the original (Mike's) LuaJIT, the latest revision from the v2.1 branch. The problem is that it doesn't support ppc64le and s390x. The existing patches doesn't apply anymore and I really don't have enough knowledge and insanity in blood to update them. Dropping these architectures would require updating many dependent aports which is not a good idea at this moment (v3.14 will be released very soon).

OpenResty's "fork" seems to be the only active LuaJIT fork that regularly synchronize changes from the upstream LuaJIT project and provides support for all architectures we need.

This is the official OpenResty branch of LuaJIT. It is not to be considered a fork, since we still regularly synchronize changes from the upstream LuaJIT project

Resolves #12410 (closed) #10478 (closed)