Merge branch 'riscv' into 'master'

.gitmodules

Cargo.lock

Cargo.toml

Makefile

cbindgen.globdefs.toml

generic-rt/src/lib.rs

include/setjmp.h

include/sys/user.h

ld_so/ld_script/riscv64gc-unknown-redox.ld

ld_so/src/lib.rs

openlibm

redox-rt/src/arch/mod.rs

redox-rt/src/arch/riscv64.rs

redox-rt/src/lib.rs

redox-rt/src/signal.rs

renamesyms.sh

src/crt0/src/lib.rs

src/crti/src/lib.rs

src/crtn/src/lib.rs

src/header/arch_riscv64_user/cbindgen.toml