[Support] Use explicit inline element count for AccelerationStructureDescs SmallVectors (#1252)

## Problem

`AccelerationStructureDescs` declares its lists with the default
`SmallVector` inline element count:

```cpp
struct AccelerationStructureDescs {
  llvm::SmallVector<BLASDesc> BLAS;
  llvm::SmallVector<TLASDesc> TLAS;
};
```

`BLASDesc` holds a `std::string` plus two further default-inlined
`SmallVector`s (`Triangles`, `AABBs`), so its size compounds. Under
MSVC's debug STL (`/MDd`, `_ITERATOR_DEBUG_LEVEL=2`), `std::string` and
the nested inline storage grow enough that `sizeof(BLASDesc)` exceeds
256 bytes, tripping LLVM's assertion in
`CalculateSmallVectorDefaultInlinedElements`:

> You are trying to use a default number of inlined elements for
`SmallVector<T>` but `sizeof(T)` is really big! Please use an explicit
number of inlined elements with `SmallVector<T, N>` ...

This breaks any **Debug** build with MSVC on Windows (`Pipeline.h` is
included widely). Release / RelWithDebInfo builds -- including CI --
keep the types under the limit, so the failure isn't visible there.

## Fix

Give the lists an explicit inline element count, as the assertion
recommends. Only `BLASDesc` trips the assert today; `TLASDesc` has the
same shape and sits just under the threshold, so it gets the same
treatment for consistency and to avoid a latent break when fields are
added. No functional change -- this only sets inline storage capacity.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: MarijnS95

include/Support/Pipeline.h

@@ -523,8 +523,8 @@ struct TLASDesc {
 };
 
 struct AccelerationStructureDescs {
-  llvm::SmallVector<BLASDesc> BLAS;
-  llvm::SmallVector<TLASDesc> TLAS;
+  llvm::SmallVector<BLASDesc, 1> BLAS;
+  llvm::SmallVector<TLASDesc, 1> TLAS;
 };
 
 struct Pipeline {