[compiler-rt] [scudo] allocation_ring_buffer_size <= 0 disables buffer (PR #71791)

[Mitch Phillips via llvm-commits]

https://github.com/hctim commented:

`compiler-rt/lib/scudo/standalone/combined.h:1494`

Also this (to avoid mapping it as well)?

```
1492   void mapAndInitializeRingBuffer() {
1493     u32 AllocationRingBufferSize =
1494         static_cast<u32>(getFlags()->allocation_ring_buffer_size);
////     Hoist this check up, and make it be |getFlags()->allocation_ring_buffer_size < 1| to avoid the
////     type punning?
1495     if (AllocationRingBufferSize < 1)
1496       return;
1497     MemMapT MemMap;
1498     MemMap.map(
1499         /*Addr=*/0U,
1500         roundUp(ringBufferSizeInBytes(AllocationRingBufferSize),
```

https://github.com/llvm/llvm-project/pull/71791