llvm-toolset:rhel8 security update

LLVM Toolset provides the LLVM compiler infrastructure framework, the Clang compiler for the C and C++ languages, the LLDB debugger, and related tools for code analysis.

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 clang in order to facilitate detection of BiDi Unicode characters:

clang-tidy now finds identifiers that contain Unicode characters with right-to-left direction, which can be confusing as they may change the understanding of a whole statement.

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: [security-medium]llvm-toolset
Stream name: rhel8