Emergency Self-Construct

@yashssh question: we are going to be merging https://github.com/numba/llvmlite/pull/1252 very soon -- would you be able to rebase this PR onto `main` at short notice this week? I'm trying to...

> Thanks @esc! Yeah I can get to it OK, great, I'll keep you posted!

@yashssh the PR @ https://github.com/numba/llvmlite/pull/1252 is now merged, I think you can merge `main` into this now and resolve the conflicts.

I saw these merge conflicts: ``` Unmerged paths: both modified: ffi/CMakeLists.txt deleted by us: ffi/Makefile.freebsd deleted by us: ffi/Makefile.linux deleted by us: ffi/Makefile.osx both modified: ffi/build.py both modified: ffi/custom_passes.cpp both...

The RTD jobs fail because of: ``` -- Found LLVM 15.0.7 --   | -- Using LLVMConfig.cmake in: /home/docs/checkouts/readthedocs.org/user_builds/llvmlite/conda/1092/lib/cmake/llvm   | CMake Error at CMakeLists.txt:41 (message):   | LLVM CMake export states LLVM...

> > The RTD jobs fail because of: > > ``` > > > > -- Found LLVM 15.0.7 > > -- > >   | -- Using LLVMConfig.cmake in: /home/docs/checkouts/readthedocs.org/user_builds/llvmlite/conda/1092/lib/cmake/llvm...

@gmarkall @sklam and @swap357 are currently working on https://github.com/numba/llvmlite/pull/1226 -- once that passes, we can build some `llvmdev` packages suitable for this PR.

@Bob-vdV thank you for suggesting this, pull-requests are welcome!

It looks like the tests are failing with the message: ``` FAIL: test_trim_zeros (numba.tests.test_np_functions.TestNPFunctions) ``` Though I am not sure why the changes in this PR would result in that...

@youssofr -- thank you for fixing up all of this. I have been tasked to pickup some stale PR for the month of June. This looks pretty far along. I...