List missing targets

[SimonSapin]

rust-lang/rust#60260 and rust-lang/rust#63155 added support for some new targets to rustc, but they’re not yet listed on https://forge.rust-lang.org/platform-support.html. I’d send a PR, but I don’t know what tier these targets are considered, or what components are available through rustup (if any).

[XAMPPRocky]

I think it's safe to say for now it's a tier 3 platform. I don't think anything is being provided through rustup at the moment.

[SimonSapin]

Looks like there’s a lot missing:

% for t in $(rustc +nightly --print target-list); (rg -qL $t tiers.yaml || echo $t)
aarch64-unknown-freebsd
aarch64-unknown-hermit
aarch64-unknown-netbsd
aarch64-unknown-none
aarch64-unknown-redox
aarch64-uwp-windows-msvc
aarch64-wrs-vxworks
armv4t-unknown-linux-gnueabi
armv6-unknown-freebsd
armv6-unknown-netbsd-eabihf
armv7-unknown-freebsd
armv7-unknown-netbsd-eabihf
armv7-wrs-vxworks-eabihf
hexagon-unknown-linux-musl
i686-unknown-dragonfly
i686-uwp-windows-gnu
i686-uwp-windows-msvc
i686-wrs-vxworks
mips64-unknown-linux-muslabi64
mips64el-unknown-linux-muslabi64
mipsisa32r6-unknown-linux-gnu
mipsisa32r6el-unknown-linux-gnu
mipsisa64r6-unknown-linux-gnuabi64
mipsisa64r6el-unknown-linux-gnuabi64
powerpc-unknown-linux-musl
powerpc-unknown-netbsd
powerpc-wrs-vxworks
powerpc-wrs-vxworks-spe
powerpc64-unknown-freebsd
powerpc64-unknown-linux-musl
powerpc64-wrs-vxworks
powerpc64le-unknown-linux-musl
riscv32i-unknown-none-elf
sparc64-unknown-openbsd
thumbv7a-pc-windows-msvc
thumbv8m.base-none-eabi
thumbv8m.main-none-eabi
thumbv8m.main-none-eabihf
wasm32-experimental-emscripten
x86_64-pc-solaris
x86_64-unknown-hermit
x86_64-unknown-l4re-uclibc
x86_64-unknown-uefi
x86_64-uwp-windows-gnu
x86_64-uwp-windows-msvc
x86_64-wrs-vxworks

[XAMPPRocky]

@SimonSapin I've added those platforms to the Rust Forge, however I didn't include their level of support as I can't test all those platforms. Would you be okay with closing this in favour of #255?