tools headers UAPI: Sync linux/in.h copy with the kernel sources

tools headers UAPI: Sync linux/in.h copy with the kernel sources

To pick the changes in:

  321827477360934d ("icmp: don't send out ICMP messages with a source address of 0.0.0.0")

That don't result in any change in tooling, as INADDR_ are not used to
generate id->string tables used by 'perf trace'.

This addresses this build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/in.h' differs from latest version at 'include/uapi/linux/in.h'
  diff -u tools/include/uapi/linux/in.h include/uapi/linux/in.h

Cc: David S. Miller <davem@davemloft.net>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>