Similar to #31840, currently our Linux toolchain file contains:
set(CMAKE_AR "aarch64-linux-gnu-ar")
set(CMAKE_RANLIB "aarch64-linux-gnu-ranlib")
set(CMAKE_STRIP "aarch64-linux-gnu-strip")
set(CMAKE_OBJCOPY "aarch64-linux-gnu-objcopy")
set(CMAKE_OBJDUMP "")
objdump is currently only used for the macOS cross build, where it's llvm-objdump, but we should be consistent in producing a toolchain file that points to actual tools, rather than leaving variables unset.
Similar to #31840, currently our Linux toolchain file contains:
```bash
set(CMAKE_AR "aarch64-linux-gnu-ar")
set(CMAKE_RANLIB "aarch64-linux-gnu-ranlib")
set(CMAKE_STRIP "aarch64-linux-gnu-strip")
set(CMAKE_OBJCOPY "aarch64-linux-gnu-objcopy")
set(CMAKE_OBJDUMP "")
```
`objdump` is currently only used for the macOS cross build, where it's
`llvm-objdump`, but we should be consistent in producing a toolchain
file that points to actual tools, rather than leaving variables unset.
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The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.
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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31857.
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ACK 2434aeab62ba07c5380112838f3600b3dbbceef2.
utACK 2434aeab62ba07c5380112838f3600b3dbbceef2