Remove empty non-virtual destructors or mark them =default when non-public

These add no value but can make a class non-trivially copyable. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234688 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DebugInfo/DWARF/DWARFUnit.h

@@ -46,7 +46,7 @@ protected:
                          const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
                          StringRef SOS, StringRef AOS, bool isLittleEndian) = 0;
 
-  ~DWARFUnitSectionBase() {}
+  ~DWARFUnitSectionBase() = default;
 };
 
 /// Concrete instance of DWARFUnitSection, specialized for one Unit type.