Kyrylo Tkachov and Richard Sandiford appointed AArch64 maintainers.

[Ramana Radhakrishnan]

Hi,

I'm pleased to announce that the GCC steering committee has appointed
Kyrylo Tkachov and Richard Sandiford as AArch64 maintainers.

Please join me in congratulating them both on their additional roles
in the community. Kyrill / Richard, please update your listings in the
MAINTAINERS file.

Thanks,
Ramana