[ADT] Use inherited ctors to forward to base. NFCI.

Author: d0k

llvm/include/llvm/ADT/SmallPtrSet.h

@@ -346,14 +346,8 @@ class SmallPtrSetImpl : public SmallPtrSetImplBase {
   using ConstPtrTraits = PointerLikeTypeTraits<ConstPtrType>;
 
 protected:
-  // Constructors that forward to the base.
-  SmallPtrSetImpl(const void **SmallStorage, const SmallPtrSetImpl &that)
-      : SmallPtrSetImplBase(SmallStorage, that) {}
-  SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize,
-                  SmallPtrSetImpl &&that)
-      : SmallPtrSetImplBase(SmallStorage, SmallSize, std::move(that)) {}
-  explicit SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize)
-      : SmallPtrSetImplBase(SmallStorage, SmallSize) {}
+  // Forward constructors to the base.
+  using SmallPtrSetImplBase::SmallPtrSetImplBase;
 
 public:
   using iterator = SmallPtrSetIterator<PtrType>;