(common-generated): Add s-proto-bp.d.
* sysdeps/unix/make-syscalls.sh: Use s-proto-bp.d for dependencies
of bp thunks.
* sysdeps/unix/s-proto-bp.S: New file.
* sysdeps/generic/bp-thunks.h: Don't include <sys/vm86.h> here.
Use <io/sys/sendfile.h> instead of <sys/sendfile.h>.
* sysdeps/unix/sysv/linux/i386/bp-thunks.h: New file.
