[llvm] [BPF] Define set of BPF libcalls (PR #169537)

[via llvm-commits]

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NinaNoco wrote:

As far as I can tell, the libcalls not included in this list will be lowered by LLVM internally, so `smul` works when the set doesn't include it, but does not when it does.

https://github.com/llvm/llvm-project/pull/169537