Auto merge of #91743 - cjgillot:enable_mir_inlining_inline_all, r=oli-obk

Enable MIR inlining

Continuation of rust-lang/rust#82280 by `@wesleywiser.`

#82280 has shown nice compile time wins could be obtained by enabling MIR inlining.
Most of the issues in rust-lang/rust#81567 are now fixed,
except the interaction with polymorphization which is worked around specifically.

I believe we can proceed with enabling MIR inlining in the near future
(preferably just after beta branching, in case we discover new issues).

Steps before merging:
- [x] figure out the interaction with polymorphization;
- [x] figure out how miri should deal with extern types;
- [x] silence the extra arithmetic overflow warnings;
- [x] remove the codegen fulfilment ICE;
- [x] remove the type normalization ICEs while compiling nalgebra;
- [ ] tweak the inlining threshold.

Author: bors