Skip passing /natvis to lld-link until supported.
### Overview
Teaching rustc about MSVC's undocumented linker flag, /NATVIS, broke rustc's compatability with LLVM's `lld-link` frontend, as it does not recognize the flag. This pull request works around the problem by excluding `lld-link` by name. @retep998 discovered this regression.
### Possible Issues
- Other linkers that try to be compatible with the MSVC linker flavor may also be broken and in need of workarounds.
- Warning about the workaround may be overkill for a minor reduction in debug functionality.
- Depending on how long this workaround sticks around, it may eventually be preferred to version check `lld-link` instead of assuming all versions are incompatible.
### Relevant issues
* Broke in https://github.com/rust-lang/rust/pull/43221 Embed MSVC .natvis files into .pdbs and mangle debuginfo for &str, *T, and [T].
* LLVM patched in 27b9c42853 to ignore the flag instead of erroring.
r? @michaelwoerister
64fa14e977