[Bug sanitizer/80797] -fsanitize=null doesn't instrument &s->x

[zeccav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80797

--- Comment #4 from Vittorio Zecca <zeccav at gmail dot com> ---
I applied your patch to version 8 trunk 247930 and it seems to work,
but on your example I get 

ubsan-1.c:10:8: runtime error: member access within null pointer of type
'struct S'
ubsan-1.c:11:8: runtime error: member access within null pointer of type
'struct S'

pointing at column 8 to v and v2.
Shouldn't they point to s or i?