drop plans with rustls [ci skip]

While this would be an interesting alternative in theory and the project
is active, related curl activity seems low and my recent attempt failed
hard when trying to (cross-)build it. This may have been entirely my own
fault/ignorance, and I did see similar happen with other Rust projects,
I don't see any reasonable way out. Short of having the stamina and free
time to spend weeks or months to crack it, for now I delete any plans to
use rustls with curl-for-win builds. Focusing instead on switching to
either LibreSSL or BoringSSL.

Author: vszakats

_build.sh

@@ -69,9 +69,6 @@ set -o xtrace -o errexit -o nounset; [ -n "${BASH:-}${ZSH_NAME:-}" ] && set -o p
 #   - Enable Control Flow Guard (once toolchains support it): -ehcontguard (requires LLVM 13.0.0)
 #   - LLVM -mretpoline
 #   - GNU multiarg options `--opt value` -> `-—opt=value`?
-#   - rustls?
-#     https://github.com/rustls/rustls/archive/refs/tags/v/0.20.6.tar.gz
-#     $ cargo build --target={x86_64-pc-windows-gnullvm,aarch64-pc-windows-gnullvm,i686-pc-windows-gnu}
 
 # Resources:
 #   - https://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html