ANDROID: CRC ABI fixups in ip.h and ipv6.h

In commit 6e933443 ("net: use struct_group to copy ip/ipv6 header
addresses"), struct_group() is added to some structures to resolve a
build warning.  This changes the CRC of a number of networking
functions, without changing any actual structure sizes or interactions.
To resolve this, use __GENKSYMS__ #ifdef hack to preserve the Android
kernel CRC abi.

This also requires an update of the .xml representation to handle the
new union structure properly, as the abi report shows the following
expected change:

type 'struct iphdr' changed
  member changed from '__be32 saddr' to 'union { struct { __be32 saddr; __be32 daddr; }; struct { __be32 saddr; __be32 daddr; } addrs; }'
    type changed from '__be32' = '__u32' = 'unsigned int' to 'union { struct { __be32 saddr; __be32 daddr; }; struct { __be32 saddr; __be32 daddr; } addrs; }'
      resolved type changed from 'unsigned int' to 'union { struct { __be32 saddr; __be32 daddr; }; struct { __be32 saddr; __be32 daddr; } addrs; }'
  member '__be32 daddr' was removed

Bug: 161946584
Fixes: 6e933443 ("net: use struct_group to copy ip/ipv6 header addresses")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ia70eb3aa41316fbced713c99c85ddaeccec2ffec