Change scno type from long to unsigned long

Change scno type from long to unsigned long

Use an unsigned type for syscall numbers as they are not intended
for signed arithmetics.  Introduce kernel_scno_t as a typedef
to unsigned long, that could be changed later to kernel_ulong_t.

* kernel_types.h (kernel_scno_t): New type, typedef to unsigned long.
* defs.h (struct tcb): Change type of scno field from long
to kernel_scno_t.
(syscall_name): Change argument type from long to kernel_scno_t.
(scno_in_range, scno_is_valid): Change argument type from unsigned long
to kernel_scno_t.
* linux/aarch64/set_scno.c (arch_set_scno): Change scno argument type
from long to kernel_scno_t.
* linux/alpha/set_scno.c (arch_set_scno): Likewise.
* linux/arc/set_scno.c (arch_set_scno): Likewise.
* linux/arm/set_scno.c (arch_set_scno): Likewise.
* linux/avr32/set_scno.c (arch_set_scno): Likewise.
* linux/bfin/set_scno.c (arch_set_scno): Likewise.
* linux/crisv10/set_scno.c (arch_set_scno): Likewise.
* linux/hppa/set_scno.c (arch_set_scno): Likewise.
* linux/i386/set_scno.c (arch_set_scno): Likewise.
* linux/ia64/set_scno.c (arch_set_scno): Likewise.
* linux/m68k/set_scno.c (arch_set_scno): Likewise.
* linux/metag/set_scno.c (arch_set_scno): Likewise.
* linux/microblaze/set_scno.c (arch_set_scno): Likewise.
* linux/mips/set_scno.c (arch_set_scno): Likewise.
* linux/nios2/set_scno.c (arch_set_scno): Likewise.
* linux/or1k/set_scno.c (arch_set_scno): Likewise.
* linux/powerpc/set_scno.c (arch_set_scno): Likewise.
* linux/riscv/set_scno.c (arch_set_scno): Likewise.
* linux/s390/set_scno.c (arch_set_scno): Likewise.
* linux/sh/set_scno.c (arch_set_scno): Likewise.
* linux/sh64/set_scno.c (arch_set_scno): Likewise.
* linux/sparc/set_scno.c (arch_set_scno): Likewise.
* linux/tile/set_scno.c (arch_set_scno): Likewise.
* linux/x86_64/set_scno.c (arch_set_scno): Likewise.
* linux/xtensa/set_scno.c (arch_set_scno): Likewise.
* linux/aarch64/get_scno.c (arch_get_scno): Change scno variable type
from long to kernel_scno_t.
* linux/alpha/get_scno.c (arch_get_scno): Likewise.
* linux/arm/get_scno.c (arch_get_scno): Likewise.
* linux/sh/get_scno.c (arch_get_scno): Likewise.
* linux/x86_64/get_scno.c (arch_get_scno): Likewise.
* syscall.c (arch_set_scno): Likewise.
(shuffle_scno): Change return type from long to kernel_scno_t.
(syscall_name): Change argument type from long to kernel_scno_t.