MFH: r553656

lang/luajit: switch to LLVM10 from ports for 12.1/amd64

12.1 shipped with LLVM 8.0.1 which links libluajit with a bogus (improperly
aligned) TLS segment offset. Notably, this breaks under 12.2 rtld and causes
a SIGBUS when an error is raised.

Since the issue is technically a broken binary, the attached patch pins
12.1/amd64 builds of luajit to devel/llvm10 so that they can be rebuilt with
a linker that will handle this properly and stop breaking luajit-dependant
applications on 12.2 while the packages are still built on 12.1. This will
naturally fall away when portmgr goes to axe conditionals solely for FreeBSD
12.1 after it goes EOL.

The src/Makefile patch has been dropped in this version in favor of just
supplying the variables it was unsetting via Make arguments as a minor
cleanup.

PR: 250707, 250726
Reported by: many
Investigation by: Andrew Gierth <andrew tao11 riddles org uk>
Confirmation from: kib
Approved by: osa (maintainer)

Approved by: ports-secteam (implicit, runtime fix)