main/luajit: use active fork, enable s390x

Let's start using Siddhesh Poyarekar's tree where development is active
and there are more fixes and features.

Note that with this commit, we start using snapshots of master branch
instead of v2.1 branch. See README for more information.

Now upstream is at https://github.com/siddhesh/LuaJIT.

Also drop the ppc64le patch since it has been reworked and rebased. Drop
luajit binary linking since it's built-in in Makefile.
6 jobs for !468 with luajit-new in 2 minutes and 28 seconds (queued for 1 second)
latest detached
Status Job ID Name Coverage
  Lint
failed #9366
docker-alpine x86_64 allowed to fail
lint

00:00:28

 
  Build
passed #9371
docker-alpine ci-build aarch64
build-aarch64

00:01:56

passed #9370
docker-alpine ci-build ppc64le
build-ppc64le

00:01:16

passed #9369
docker-alpine ci-build s390x
build-s390x

00:01:58

passed #9368
docker-alpine ci-build x86
build-x86

00:01:40

passed #9367
docker-alpine ci-build x86_64
build-x86_64

00:01:15

 
Name Stage Failure
failed
lint Lint
No job log