rust-toolset:rhel8 security update

Rust Toolset provides the Rust programming language compiler rustc, the cargo build tool and dependency manager, and required libraries.

Security Fix(es):

* Developer environment: Unicode's bidirectional (BiDi) override characters can cause trojan source attacks (CVE-2021-42574)

The following changes were introduced in rust in order to facilitate detection of BiDi Unicode characters:

Rust introduces two new lints to detect and reject code containing the affected codepoints. These new deny-by-default lints detect affected codepoints in string literals and comments. The lints will prevent source code file containing these codepoints from being compiled. If your code has legitimate uses for the codepoints we recommend replacing them with the related escape sequence. The error messages will suggest the right escapes to use.

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

CVE-2021-42574
An issue was discovered in the Bidirectional Algorithm in the Unicode Specification through 14.0. It permits the visual reordering of characters via control sequences, which can be used to craft source code that renders different logic than the logical ordering of tokens ingested by compilers and interpreters. Adversaries can leverage this to encode source code for compilers accepting Unicode such that targeted vulnerabilities are introduced invisibly to human reviewers.

Modularity name: rust-toolset
Stream name: rhel8