[compiler-rt] [asan] Plumb may_return_null through Allocator::Allocate/asan_memalign (PR #196413)

[David Justo via llvm-commits]

================
@@ -798,7 +802,8 @@ struct Allocator {
     thread_stats.reallocs++;
     thread_stats.realloced += new_size;
 
-    void *new_ptr = Allocate(new_size, 8, stack, FROM_MALLOC, true);
+    void* new_ptr = Allocate(new_size, 8, stack, FROM_MALLOC, /*can_fill=*/true,
----------------
davidmrdavid wrote:

nit / subjective:
while you're at it (I noticed you added `/*can_fill*/`, it would be great to `/* comment /*` that `8`, as:
```suggestion
    void* new_ptr = Allocate(new_size, /*alignment=*/ 8, stack, FROM_MALLOC, /*can_fill=*/true,
```

(other such opportunities in the diff as well)

https://github.com/llvm/llvm-project/pull/196413