devel/rustup-init: Update 1.28.1 => 1.29.1

While here:

• Add linked libraries from ldd output to LIB_DEPENDS.
• Unbundle OpenSSL.
• Add TESTING_UNSAFE.

Changelog:
https://github.com/rust-lang/rustup/blob/1.29.1/CHANGELOG.md

PR: 298213
Approved by: osa, vvd (Mentors, implicit)
Co-authored-by: Ian Wagner <ianthetechie@gmail.com>