[llvm] [Support] Resolve symlinks in `getMainExecutable()` on Windows (PR #76304)

[Mike Hommey via llvm-commits]

glandium wrote:

It probably has the "contains spaces" problem on Linux. I guess `sys::printArg` would make sense for everything llvm-config prints out, but there's no saying whether things that consume its output will actually deal with it correctly (although, obviously, they're probably not handling things correctly anyways for the case `sys::printArg` would print something different).

https://github.com/llvm/llvm-project/pull/76304