Fix failing test_rlib_dep_reader_call for omit CARGO_HOME

[Felixoid]

Fixes #2303

If the CARGO_HOME is empty, but rustc is installed globally, it will be used in the compiler::rust::test::test_rlib_dep_reader_call.

Now, the test fails as:

---- compiler::rust::test::test_rlib_dep_reader_call stdout ----

thread 'compiler::rust::test::test_rlib_dep_reader_call' panicked at src/compiler/rust.rs:3321:33:
called `Result::unwrap()` on an `Err` value: No such file or directory (os error 2)

[sylvestre]

is it possible to add a test to make sure it doesn't regress? thanks

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 71.06%. Comparing base (cd7dcd5) to head (2b462da).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/compiler/rust.rs	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2527      +/-   ##
==========================================
+ Coverage   71.04%   71.06%   +0.01%     
==========================================
  Files          64       64              
  Lines       35369    35396      +27     
==========================================
+ Hits        25128    25154      +26     
- Misses      10241    10242       +1     

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[Felixoid]

I don't know how to do it. The test is environment-dependent, so what should the regression test do?

Neither of rustc in $PATH nor $CARGO_home/bin/rustc looks mandatory to me. It's unclear how the regression can be caught.