This adds `lean.h.bc`, a LLVM bitcode file of the Lean
runtime that is to be inlined. This is programatically generated.
1. This differs from the previous `libleanrt.ll`, since it produces an
LLVM bitcode file, versus a textual IR file. The bitcode file
is faster to parse and build an in-memory LLVM module from.
2. We build `lean.h.bc` by adding it as a target to `shell`,
which ensures that it is always built.
3. We eschew the need for:
```cpp
```
which causes breakage in the build, since changing the meaning of
`static` messes with definitions in the C++ headers.
Instead, we build `lean.h.bc` by copying everything in
`src/include/lean/lean.h`, renaming `inline` to
`__attribute__(alwaysinline)` [which forces LLVM to generate
`alwaysinline` annotations], then running the `-O3` pass pipeline
to get reasonably optimised IR, and will be perfectly inlined
when linked into the generated LLVM code by
`src/Lean/Compiler/IR/EmitLLVM.lean`.
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
dfb5548cab