Use SmallPtrSet after deprecation (#3329)

Update for llvm-project commit `9b493dcad259` ("[ADT] Deprecate the
redirection from SmallSet to SmallPtrSet (Take 2) (#155078)",
2025-08-23).

Author: svenvh

lib/SPIRV/SPIRVReader.cpp

@@ -56,7 +56,7 @@
 #include "VectorComputeUtil.h"
 
 #include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/BinaryFormat/Dwarf.h"
@@ -829,7 +829,7 @@ void SPIRVToLLVM::setLLVMLoopMetadata(const LoopInstType *LM,
     // Create index group metadata nodes - one per each of the array
     // variables. Mark each GEP accessing a particular array variable
     // into a corresponding index group
-    std::map<unsigned, SmallSet<MDNode *, 4>> SafelenIdxGroupMap;
+    std::map<unsigned, SmallPtrSet<MDNode *, 4>> SafelenIdxGroupMap;
     // Whenever a kernel closure field access is pointed to instead of
     // an array/pointer variable, ensure that all GEPs to that memory
     // share the same index group by hashing the newly added index groups.