Rustc outputs LLVM IR that contains llvm intrinsics that should be inlined

[jackcmay]

This results in external call references in the BPF assembly code:

This is normally taken care of by the linker who will implementations of the necessary intrinsics into the resulting binary/shared module. In our case, we are compiling to BPF which stops at the .o stage and does not continue to the final linked binary/shared module.

Possible solutions:

• Custom compilation pass that inlines references to the intrinsic calls with equivalent in-lined code
• Export equivalent helper calls from the bpf vm so that they are resolved at run-time.
• Enhance rustc to pass -fno-builtin or maybe -always-inline through to llvm which should result in equivalent in-lined code in place of all intrinsics and builtins.

[jackcmay]

Included in #2178