virprocess: Extend list of platforms for setns wrapper

virprocess: Extend list of platforms for setns wrapper

Currently, the setns() wrapper is supported only for x86_64 and i686
which leaves us failing to build on other platforms like arm, aarch64
and so on. This means, that the wrapper needs to be extended to those
platforms and make to fail on runtime not compile time.

The syscall numbers for other platforms was fetched using this
command:

kernel.git $ git grep "define.*__NR_setns" | grep -e arm -e powerpc -e s390
arch/arm/include/uapi/asm/unistd.h:#define __NR_setns                   (__NR_SYSCALL_BASE+375)
arch/arm64/include/asm/unistd32.h:#define __NR_setns 375
arch/powerpc/include/uapi/asm/unistd.h:#define __NR_setns               350
arch/s390/include/uapi/asm/unistd.h:#define __NR_setns          339

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>