[AppleAccelTable][NFC] Remove struct keyword from member decl

This is only needed in C.

Depends on D151989

Differential Revision: https://reviews.llvm.org/D152155

Author: felipepiovezan

llvm/include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h

@@ -103,8 +103,8 @@ class AppleAcceleratorTable : public DWARFAcceleratorTable {
     extractOffset(std::optional<DWARFFormValue> Value) const;
   };
 
-  struct Header Hdr;
-  struct HeaderData HdrData;
+  Header Hdr;
+  HeaderData HdrData;
   bool IsValid = false;
 
   /// Returns true if we should continue scanning for entries or false if we've