perf annotate-data: Improve type comparison from different scopes

perf annotate-data: Improve type comparison from different scopes

When comparing types from different scopes, first compare their type
offsets. A larger offset means the field belongs to an outer (enclosing)
struct. This helps resolve cases where a pointer is found in an inner
scope, but a struct containing that pointer exists in an outer scope.
Previously, is_better_type would prefer the pointer type, but the struct
type is actually more complete and should be chosen.

Prefer types from outer scopes when is_better_type cannot determine a
better type. This is a heuristic for the case `struct A { struct B; }`
where A and B have the same size but I think in most cases A is in the
outer scope and should be preferred.

Signed-off-by: Zecheng Li <zecheng@google.com>
Signed-off-by: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>