I'm trying to get all our ports up to date with the latest stable
versions, just for my own sanity. This handles glibc, but pushes Linux
a bit past what's currently stable.
These are cached from riscv-linux and have gotten out of date. The
breaking change was in asm/ptrace.h, but riscv-linux also got bumped so
this is a big commit.
This syncs from e1c1614e7bd2e053e88d0cb875e1a22b27df6e39 in riscv-linux.