9pex: don't compile the client
Merge commit 'd4afafed9b155b504d29c72755e2987a0724f461'
Squashed 'c9/' changes from 24bfa2e..8a22517
add c9 as a subtree
Merge commit 'c19685c19ee0eb9c9bcfe8d89ab1fea5231216ea' as 'c9'
Squashed 'c9/' content from commit 24bfa2e
add a note re musl+chroot
don't report an error on eof
make valgrind happier