Maintain new Armv8-R AArch64 targets

[jonathanpallant]

rust-lang/rust#150863 adds aarch64v8r-unknown-none and aarch64v8r-unknown-none-softfloat targets Armv8-R AArch64 bare-metal. I'm proposing that EDWG is listed as a maintainer, as they already maintain the aarch64-unknown-none targets.

• @adamgreig
• @bartmassey
• @berkus
• @jonathanpallant
• @nchong-at-aws
• @newAM
• @raw-bin
• @robamu
• @thalesfragoso
• @therealprof
• @ithinuel
• @davidtwco (representing @rust-lang/arm-maintainers)

[BartMassey]

I am all for this, but I have to warn you that I have no idea how ARM-R works at this point; I'll do what I can, but…

[jonathanpallant]

The good news is that from a target point of view, Armv8-R AArch64 is just the Armv8-A AArch64 you already know and love, with a few features changed from optional to mandatory.

The main practical difference is that the R-profile systems don't have an MMU so they will be used to do microcontroller style things, like run RTIC or Embassy or an RTOS. But we know how to do that already.

[adamgreig]

It's been two weeks with more than 50% approval and no objections, so this proposal is now considered accepted, thank you!