Build Filecheck is packaged instead of target for the LLVM tools downloaded from CI during build for cross-compiled targets.

[luqmana]

I don't have Rosetta 2 enabled so I ran into a bit of confusion trying to run some codegen tests on an M1 MacBook.

Looking at the LLVM binaries that were downloaded, FileCheck seems to be the odd one out:

$ file build/aarch64-apple-darwin/ci-llvm/bin/*
build/aarch64-apple-darwin/ci-llvm/bin/FileCheck:       Mach-O 64-bit executable x86_64
build/aarch64-apple-darwin/ci-llvm/bin/lld:             Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-ar:         Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-bcanalyzer: Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-config:     Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-cov:        Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-dwp:        Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-nm:         Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-objdump:    Mach-O 64-bit executable arm64
build/aarch64-apple-darwin/ci-llvm/bin/llvm-profdata:   Mach-O 64-bit executable arm64

Building LLVM locally definitely generates the right version, compare:

$ file ./aarch64-apple-darwin/{ci-,}llvm/bin/FileCheck
./aarch64-apple-darwin/ci-llvm/bin/FileCheck: Mach-O 64-bit executable x86_64
./aarch64-apple-darwin/llvm/bin/FileCheck:    Mach-O 64-bit executable arm64

[luqmana]

Looks like it isn't just mac (or really aarch64). It's more about which have been cross-compiled. As an example of another cross-compiled target there's aarch64-pc-windows-msvc:

$ file bin/*      
bin/FileCheck.exe:       PE32+ executable (console) x86-64, for MS Windows
bin/lld.exe:             PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-ar.exe:         PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-bcanalyzer.exe: PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-config.exe:     PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-cov.exe:        PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-dwp.exe:        PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-nm.exe:         PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-objdump.exe:    PE32+ executable (console) Aarch64, for MS Windows
bin/llvm-profdata.exe:   PE32+ executable (console) Aarch64, for MS Windows