Auto merge of #141435 - RalfJung:unsupported_calling_conventions, r=workingjubilee

Add (back) `unsupported_calling_conventions` lint to reject more invalid calling conventions

This adds back the `unsupported_calling_conventions` lint that was removed in rust-lang/rust#129935, in order to start the process of dealing with rust-lang/rust#137018. Specifically, we are going for the plan laid out [here](rust-lang/rust#137018 (comment)):
- thiscall, stdcall, fastcall, cdecl should only be accepted on x86-32
- vectorcall should only be accepted on x86-32 and x86-64

The difference to the status quo is that:
- We stop accepting stdcall, fastcall on targets that are windows && non-x86-32 (we already don't accept these on targets that are non-windows && non-x86-32)
- We stop accepting cdecl on targets that are non-x86-32
- (There is no difference for thiscall, this was already a hard error on non-x86-32)
- We stop accepting vectorcall on targets that are windows && non-x86-*

Vectorcall is an unstable ABI so we can just make this a hard error immediately. The others are stable, so we emit the `unsupported_calling_conventions` forward-compat lint. I set up the lint to show up in dependencies via cargo's future-compat report immediately, but we could also make it show up just for the local crate first if that is preferred.

try-job: i686-msvc-1
try-job: x86_64-msvc-1
try-job: test-various

Author: bors