[native_toolchain_c][native_assets_builder] Consider adding paths to command-line utilities

[dcharkes]

It would be nice if package:native_toolchain_c could rely on readelf, objdump, nm, etc. being available.

We've got two options to do this:

1. Finally introduce our hook/doctor.dart and have package:native_toolchain_c discover the tools directly.
2. Pass them in via config.nativeConfig.cCompiler.
3. Do both, prefer 2, fall back to 1. (Which is what we do for the compiler, archiver, and linker.)

This would enable us to write expectXXX for package:native_toolchain_c that users can use.

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It would be nice if package:native_assets_builder could rely on readelf, objdump, nm, etc. being available.

We've got two options to do this:

1. Discover the tools directly on the file system.
2. Pass them in via config.nativeConfig.cCompiler.
3. Do both, prefer 2, fall back to 1. (Which is what we do for the compiler, archiver, and linker.)

This would enable us to write checks in the bundling tools that the dylibs are correct. #1740 (comment)

• correct target arch
• enough page size of Android
• ...

[mkustermann]

Just to clarify, the comment I made regarding verifying that shared library page size is correct for android (see #1740 (comment)) can be done without those tools.

The ELF format isn't that complicated and we could have a bit of logic that just reads it, not requiring users to have objdump etc installed