[DebugInfo] Remove an unused method DWARFUnit::getDWARF5HeaderSize(). NFC.

[ikudrin]

Summary

The method was initially added for DWARFVerifier::verifyUnitHeader() but its results were never actually used.

[probinson]

LGTM. Nice to kill off dead code!

llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h

case dwarf::DW_UT_skeleton:
       return Tag == dwarf::DW_TAG_skeleton_unit;
     case dwarf::DW_UT_split_compile:
     case dwarf::DW_UT_split_type:
       return dwarf::isUnitType(Tag);
     }
     return false;
   }
 
-  /// Return the number of bytes for the header of a unit of
-  /// UnitType type.
-  ///
-  /// This function must be called with a valid unit type which in
-  /// DWARF5 is defined as one of the following six types.
-  static uint32_t getDWARF5HeaderSize(uint8_t UnitType) {
-    switch (UnitType) {
-    case dwarf::DW_UT_compile:
-    case dwarf::DW_UT_partial:
-      return 12;
-    case dwarf::DW_UT_skeleton:
-    case dwarf::DW_UT_split_compile:
-      return 20;
-    case dwarf::DW_UT_type:
-    case dwarf::DW_UT_split_type:
-      return 24;
-    }
-    llvm_unreachable("Invalid UnitType.");
-  }
-
   llvm::Optional<object::SectionedAddress> getBaseAddress();
 
   DWARFDie getUnitDIE(bool ExtractUnitDIEOnly = true) {
     extractDIEsIfNeeded(ExtractUnitDIEOnly);
     if (DieArray.empty())
       return DWARFDie();
     return DWARFDie(this, &DieArray[0]);
   }