ANDROID: Fix abi issues in struct sk_buff

In commit 18685451fc4e ("inet: inet_defrag: prevent sk release while
still in use"), struct sk_buff dropped an unneeded union structure.
This did not change the actual structure size or layout at all, but the
abi checker didn't like it.  So trick it by putting some __GENKSYMS__
markers in to preserve the abi correctly.

Bug: 335584858
Fixes: 18685451fc4e ("inet: inet_defrag: prevent sk release while still in use")
Change-Id: I78ca54f9df3e03cccebc326babf1d84ccb5dc781
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

android/abi_gki_aarch64.stg

@@ -41288,11 +41288,6 @@ member {
   id: 0x3e4f626d
   type_id: 0x7613f9a7
 }
-member {
-  id: 0x3e5d0376
-  type_id: 0x765a5eef
-  offset: 192
-}
 member {
   id: 0x3e670f18
   type_id: 0x76b2536c
@@ -111885,11 +111880,6 @@ member {
   type_id: 0x18bd6530
   offset: 4992
 }
-member {
-  id: 0x0e850e04
-  name: "ip_defrag_offset"
-  type_id: 0x6720d32f
-}
 member {
   id: 0xbc6a844a
   name: "ip_epilogue"
@@ -218986,15 +218976,6 @@ struct_union {
     member_id: 0xa70d7362
   }
 }
-struct_union {
-  id: 0x765a5eef
-  kind: UNION
-  definition {
-    bytesize: 8
-    member_id: 0x828c89b5
-    member_id: 0x0e850e04
-  }
-}
 struct_union {
   id: 0x7689fdd5
   kind: UNION
@@ -258615,7 +258596,7 @@ struct_union {
   definition {
     bytesize: 248
     member_id: 0x34366909
-    member_id: 0x3e5d0376
+    member_id: 0x828c817c
     member_id: 0x318fd08b
     member_id: 0x53e7b9ea
     member_id: 0x345f6930

include/linux/skbuff.h

@@ -872,7 +872,14 @@ struct sk_buff {
 		struct llist_node	ll_node;
 	};
 
+#ifdef __GENKSYMS__
+	union {
+		struct sock		*sk;
+		int			ip_defrag_offset;
+	};
+#else
 	struct sock		*sk;
+#endif
 
 	union {
 		ktime_t		tstamp;

net/ipv4/inet_fragment.c

@@ -24,7 +24,9 @@
 #include <net/ip.h>
 #include <net/ipv6.h>
 
+#ifndef __GENKSYMS__
 #include "../core/sock_destructor.h"
+#endif
 
 /* Use skb->cb to track consecutive/adjacent fragments coming at
  * the end of the queue. Nodes in the rb-tree queue will