rust-toolset:rhel8 security, bug fix, and enhancement update

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

The following packages have been upgraded to a later upstream version: rust (1.52.1).

Security Fix(es):

* rust: optimization for joining strings can cause uninitialized bytes to be exposed (CVE-2020-36323)
* rust: heap-based buffer overflow in read_to_end() because it does not validate the return value from Read in an unsafe context (CVE-2021-28875)
* rust: panic safety issue in Zip implementation (CVE-2021-28876)
* rust: memory safety violation in Zip implementation for nested iter::Zips (CVE-2021-28877)
* rust: memory safety violation in Zip implementation when next_back() and next() are used together (CVE-2021-28878)
* rust: integer overflow in the Zip implementation can lead to a buffer overflow (CVE-2021-28879)
* rust: double free in Vec::from_iter function if freeing the element panics (CVE-2021-31162)

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.

For information on usage, see Using Rust Toolset linked in the References section.

CVE-2020-36323
In the standard library in Rust before 1.52.0, there is an optimization for joining strings that can cause uninitialized bytes to be exposed (or the program to crash) if the borrowed string changes after its length is checked.
CVE-2021-28875
In the standard library in Rust before 1.50.0, read_to_end() does not validate the return value from Read in an unsafe context. This bug could lead to a buffer overflow.
CVE-2021-28876
In the standard library in Rust before 1.52.0, the Zip implementation has a panic safety issue. It calls __iterator_get_unchecked() more than once for the same index when the underlying iterator panics (in certain conditions). This bug could lead to a memory safety violation due to an unmet safety requirement for the TrustedRandomAccess trait.
CVE-2021-28877
In the standard library in Rust before 1.51.0, the Zip implementation calls __iterator_get_unchecked() for the same index more than once when nested. This bug can lead to a memory safety violation due to an unmet safety requirement for the TrustedRandomAccess trait.
CVE-2021-28878
In the standard library in Rust before 1.52.0, the Zip implementation calls __iterator_get_unchecked() more than once for the same index (under certain conditions) when next_back() and next() are used together. This bug could lead to a memory safety violation due to an unmet safety requirement for the TrustedRandomAccess trait.
CVE-2021-28879
In the standard library in Rust before 1.52.0, the Zip implementation can report an incorrect size due to an integer overflow. This bug can lead to a buffer overflow when a consumed Zip iterator is used again.
CVE-2021-31162
In the standard library in Rust before 1.52.0, a double free can occur in the Vec::from_iter function if freeing the element panics.

Modularity name: rust-toolset
Stream name: rhel8