[clang][Interp][NFC] Add comments to Descriptor ctors

I can't tell these apart every time I look at them.

Author: tbaederr

clang/lib/AST/Interp/Descriptor.cpp

@@ -221,6 +221,7 @@ static BlockMoveFn getMoveArrayPrim(PrimType Type) {
   COMPOSITE_TYPE_SWITCH(Type, return moveArrayTy<T>, return nullptr);
 }
 
+/// Primitives.
 Descriptor::Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD,
                        bool IsConst, bool IsTemporary, bool IsMutable)
     : Source(D), ElemSize(primSize(Type)), Size(ElemSize),
@@ -231,6 +232,7 @@ Descriptor::Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD,
   assert(Source && "Missing source");
 }
 
+/// Primitive arrays.
 Descriptor::Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD,
                        size_t NumElems, bool IsConst, bool IsTemporary,
                        bool IsMutable)
@@ -243,6 +245,7 @@ Descriptor::Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD,
   assert(Source && "Missing source");
 }
 
+/// Primitive unknown-size arrays.
 Descriptor::Descriptor(const DeclTy &D, PrimType Type, bool IsTemporary,
                        UnknownSize)
     : Source(D), ElemSize(primSize(Type)), Size(UnknownSizeMark), MDSize(0),
@@ -252,6 +255,7 @@ Descriptor::Descriptor(const DeclTy &D, PrimType Type, bool IsTemporary,
   assert(Source && "Missing source");
 }
 
+/// Arrays of composite elements.
 Descriptor::Descriptor(const DeclTy &D, Descriptor *Elem, MetadataSize MD,
                        unsigned NumElems, bool IsConst, bool IsTemporary,
                        bool IsMutable)
@@ -264,6 +268,7 @@ Descriptor::Descriptor(const DeclTy &D, Descriptor *Elem, MetadataSize MD,
   assert(Source && "Missing source");
 }
 
+/// Unknown-size arrays of composite elements.
 Descriptor::Descriptor(const DeclTy &D, Descriptor *Elem, bool IsTemporary,
                        UnknownSize)
     : Source(D), ElemSize(Elem->getAllocSize() + sizeof(InlineDescriptor)),
@@ -274,6 +279,7 @@ Descriptor::Descriptor(const DeclTy &D, Descriptor *Elem, bool IsTemporary,
   assert(Source && "Missing source");
 }
 
+/// Composite records.
 Descriptor::Descriptor(const DeclTy &D, Record *R, MetadataSize MD,
                        bool IsConst, bool IsTemporary, bool IsMutable)
     : Source(D), ElemSize(std::max<size_t>(alignof(void *), R->getFullSize())),