all: cosmetic cleanups

src/util/xspan_impl_common.h

@@ -443,7 +443,7 @@ public: // raw access
         return ptr;
     }
 
-    // like C++ std::span
+    // like C++20 std::span
     pointer data() const noexcept { return ptr; }
     pointer data(size_t bytes) const { return raw_bytes(bytes); } // UPX extra
     // size_type size() const { return size_bytes() / sizeof(element_type); } // NOT USED