[asan] Restore check removed by r332033
Needed by fiber handling code, and possibly other code paths.
@@ -117,6 +117,8 @@ class AsanThread {
return nullptr;
if (atomic_load(&stack_switching_, memory_order_relaxed))
return nullptr;
+ if (!has_fake_stack())
+ return AsyncSignalSafeLazyInitFakeStack();
return fake_stack_;
}
