tools headers uapi: Update linux/in.h copy

To get the changes in:

  65b32f80 ("uapi: move IPPROTO_L2TP to in.h")
  5854a09b ("net/ipv4: Use __DECLARE_FLEX_ARRAY() helper")

That ends up automatically adding the new IPPROTO_L2TP to the socket
args beautifiers:

  $ tools/perf/trace/beauty/socket.sh > before
  $ cp include/uapi/linux/in.h tools/include/uapi/linux/in.h
  $ tools/perf/trace/beauty/socket.sh > after
  $ diff -u before after
  --- before	2022-10-25 12:17:02.577892416 -0300
  +++ after	2022-10-25 12:17:10.806113033 -0300
  @@ -20,6 +20,7 @@
   	[98] = "ENCAP",
   	[103] = "PIM",
   	[108] = "COMP",
  +	[115] = "L2TP",
   	[132] = "SCTP",
   	[136] = "UDPLITE",
   	[137] = "MPLS",
  $

Now 'perf trace' will decode that 115 into "L2TP" and it will also be
possible to use it in tracepoint filter expressions.

Addresses this tools/perf 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: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Wojciech Drewek <wojciech.drewek@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/lkml/Y1f%2FGe6vjQrGjYiK@kernel.org/Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/uapi/linux/in.h

@@ -68,6 +68,8 @@ enum {
 #define IPPROTO_PIM		IPPROTO_PIM
   IPPROTO_COMP = 108,		/* Compression Header Protocol		*/
 #define IPPROTO_COMP		IPPROTO_COMP
+  IPPROTO_L2TP = 115,		/* Layer 2 Tunnelling Protocol		*/
+#define IPPROTO_L2TP		IPPROTO_L2TP
   IPPROTO_SCTP = 132,		/* Stream Control Transport Protocol	*/
 #define IPPROTO_SCTP		IPPROTO_SCTP
   IPPROTO_UDPLITE = 136,	/* UDP-Lite (RFC 3828)			*/
@@ -188,21 +190,13 @@ struct ip_mreq_source {
 };
 
 struct ip_msfilter {
+	__be32		imsf_multiaddr;
+	__be32		imsf_interface;
+	__u32		imsf_fmode;
+	__u32		imsf_numsrc;
 	union {
-		struct {
-			__be32		imsf_multiaddr_aux;
-			__be32		imsf_interface_aux;
-			__u32		imsf_fmode_aux;
-			__u32		imsf_numsrc_aux;
-			__be32		imsf_slist[1];
-		};
-		struct {
-			__be32		imsf_multiaddr;
-			__be32		imsf_interface;
-			__u32		imsf_fmode;
-			__u32		imsf_numsrc;
-			__be32		imsf_slist_flex[];
-		};
+		__be32		imsf_slist[1];
+		__DECLARE_FLEX_ARRAY(__be32, imsf_slist_flex);
 	};
 };