Stepping down as maintainer for ARC and Epiphany

[Joern Rennecke]

I haven't worked with these targets in years and can't really do sensible maintenance or reviews of patches for them.
I am currently working on optimizations for other ports like RISC-V.

ARC has still an active maintainer in Claudiu Zissulescu, so is basically unaffected.
I am not aware of any ongoing development of or for Epiphany. We might consider depreciating it unless there are other takers.

I would like to downgrade my status to general write-after-approval for now.

I tried to do this myself, but there seems to be a problem with my authenticated git access; I've already sent an email to overseers.