[lsan] Ignore inderect leaks referenced by suppressed blocks

This makes suppression list to work similar to __lsan_ignore_object.

Existing behavior was inconsistent and very inconvenient for complex
data structures.

Example:

struct B;
struct A { B* ptr; };
A* t = makeA();
t->ptr = makeB();

Before the patch: if makeA suppressed by suppression file, lsan will
still report the makeB() leak, so we need two suppressions.

After the patch: a single makeA suppression is enough (the same as a
single __lsan_ignore_object(t)).

Differential Revision: https://reviews.llvm.org/D93884