lang/rust: Update to 1.52.1

• Add 32-bit powerpc support from bdragon@
• Unbreak build with LibreSSL 3.3.x [1]
• Add an update script

Changes: https://blog.rust-lang.org/2021/05/06/Rust-1.52.0.html
Changes: https://blog.rust-lang.org/2021/05/10/Rust-1.52.1.html
PR: 255608, 255652 [1]
Reviewed by: mikael, pkubaj
Exp-run by: antoine
Differential Revision: https://reviews.freebsd.org/D30099