[llvm] Reduce llvm-gsymutil memory usage (PR #140740)

[David Blaikie via llvm-commits]

dwblaikie wrote:

> Previous approach with assert(f();return success;) failed tests for release builds, so I created a separate helper. Open to suggestions how to solve this more elegantly.

Yeah, no need for a separate function - but don't do required work inside an assertion, so doing something like this instead... actually, no, since you're getting an `llvm::Error` back, you can't use an assertion to check an `llvm::Error` (otherwise the error will go unchecked in a non-asserts build, and that's bad)

So you should replace the `assert` from the original code, with `cantFail` ( https://llvm.org/docs/ProgrammersManual.html#using-cantfail-to-simplify-safe-callsites ).

https://github.com/llvm/llvm-project/pull/140740