A recent change to the Makefile.in for riscv resulted in the
machine/syscall.h header not being installed. This updates the file
to install this file again.
Signed-off-by: Simon Cook <simon.cook@embecosm.com>
PR 29515 points out our documentation builds are broken, let's just move
over to the new non-recursive builds.
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>