Auto merge of #80839 - tblah:riscv64linux_links, r=Mark-Simulacrum

Auto merge of #80839 - tblah:riscv64linux_links, r=Mark-Simulacrum

Riscv64linux Test fixes

Get tests passing again using the riscv64gc-unknown-linux-gnu docker image.

Test with
```
src/ci/docker/run.sh riscv64gc-linux
```

## linkcheck
Linkcheck tests that interdocument links in the documentation are correct. Some interdocument links go between rustc and tools (such as rustdoc and cargo). When cross compiling, rustc is built for the host while some tools are built for the target. This goes for the documentation too. Because of this, links in the rustc documentation reffering to cargo or rustdoc documentation look broken.

This issue is worked around by disabling linkcheck for cross compilation builds.

## run-make tests

#78911 seems to happen because `--target` was not passed to `rustc`, but the target linker was specified, causing the target linker to be called with options intended for the host.

Resolves #78911

In a separate issue, `issue-36710` was trying to run a binary built for the target on the host system. This will not work for any platform using `remote-test-server`/`client` (such as riscv64). I don't know of a way of skipping those platforms specifically, so I set this test to skip only on riscv64 for now.