Bump SYS_socket_subcall from 400 to 500

Bump SYS_socket_subcall from 400 to 500

Make room for syscalls that are going to be introduced in Linux 5.1.

* linux/i386/syscallent.h (SYS_socket_subcall): Raise from 400 to 500.
* linux/m68k/syscallent.h: Likewise.
* linux/powerpc/syscallent.h: Likewise.
* linux/powerpc64/syscallent.h: Likewise.
* linux/s390/syscallent.h: Likewise.
* linux/s390x/syscallent.h: Likewise.
* linux/sh/syscallent.h: Likewise.
* linux/sh64/syscallent.h: Likewise.
* linux/sparc/syscallent.h: Likewise.
* linux/sparc64/syscallent.h: Likewise.
* linux/mips/syscallent-o32.h (SYS_socket_subcall): Raise from 4400
to 4500.
* linux/mips/syscallent-n64.h (SYS_socket_subcall): Raise from 5400
to 5500.
* linux/mips/syscallent-n32.h (SYS_socket_subcall): Raise from 6400
to 6500.