doc: Point out common problem installing c2rust

[chrysn]

Contribution description

This is a simple doc update to point users in the right direction when they see something like:

  -- Could NOT find LibEdit (missing: LibEdit_INCLUDE_DIRS LibEdit_LIBRARIES) 
  -- Could NOT find LibEdit (missing: LibEdit_INCLUDE_DIRS LibEdit_LIBRARIES) 
  -- Configuring incomplete, errors occurred!

  --- stderr
  CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
    Compatibility with CMake < 3.5 will be removed from a future version of
    CMake.

    Update the VERSION argument <min> value or use a ...<max> suffix to tell
    CMake that the project does not need compatibility with older versions.


  CMake Error at /usr/lib/llvm-14/lib/cmake/clang/ClangTargets.cmake:756 (message):
    The imported target "clangBasic" references the file

       "/usr/lib/llvm-14/lib/libclangBasic.a"

    but this file does not exist.  Possible reasons include:

    * The file was deleted, renamed, or moved to another location.

    * An install or uninstall procedure did not complete successfully.

    * The installation package was faulty and contained

       "/usr/lib/llvm-14/lib/cmake/clang/ClangTargets.cmake"

    but not all the files it references.

  Call Stack (most recent call first):
    /usr/lib/cmake/clang-14/ClangConfig.cmake:19 (include)
    CMakeLists.txt:62 (find_package)


  thread 'main' panicked at /home/chrysn/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cmake-0.1.51/src/lib.rs:1100:5:

  command did not execute successfully, got: exit status: 1

  build script failed, must exit now
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Testing procedure

Look at the documentation.

More context

After c2rust newer than 0.18 is released, cargo install c2rust without git should work -- but that may take some more time on the part of the maintainers (and while it worked until a few weeks ago, when both the published and the git version broke, I didn't even update the docs before).

[riot-ci]

Murdock results

✔️ PASSED

ae0c942 doc: Point out common problem installing c2rust

Success	Failures	Total	Runtime
1	0	1	01m:32s

Artifacts

• Documentation preview

[chrysn]

Documentation deep link: https://ci.riot-os.org/results/6d84459b90cd44cd94546f9328672afd/doc-preview/using-rust.html

Rebased onto master to avoid the sanity check. (I guess all old PRs will need to rebase or merge in master to continue…).