network: avoid including sys/sysctl.h on Linux
network: avoid including sys/sysctl.h on Linux

The sys/sysctl.h header is only needed on BSD platforms to get
the sysctlbyname() function declaration. On Linux we talk to
procfs instead to change sysctls.

Unfortunately a legacy sys/sysctl.h header does exist on Linux
and including it has recently started triggering a deprecation
warning from glibc.

Protect its inclusion with a HAVE_SYSCTLBYNAME check instead
so that it only gets used on platforms where we need that
function declaration.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

zippy2/libvirt,olafhering/libvirt,eskultety/libvirt,jfehlig/libvirt,jardasgit/libvirt,zippy2/libvirt,andreabolognani/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,libvirt/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,eskultety/libvirt,eskultety/libvirt,crobinso/libvirt,zippy2/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,crobinso/libvirt,olafhering/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,nertpinx/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,andreabolognani/libvirt,eskultety/libvirt,jfehlig/libvirt,zippy2/libvirt,andreabolognani/libvirt,jardasgit/libvirt,crobinso/libvirt,olafhering/libvirt,fabianfreyer/libvirt,crobinso/libvirt,nertpinx/libvirt,nertpinx/libvirt,andreabolognani/libvirt