Everywhere: Turn #if *_DEBUG into dbgln_if/if constexpr

Author: https://github.com/gunnarbeutner
Commit: 6cf59b6ae9
Pull-request: https://github.com/SerenityOS/serenity/pull/6796

Userland/Libraries/LibGfx/JPGLoader.cpp

@@ -247,9 +247,7 @@ static Optional<u8> get_next_symbol(HuffmanStreamState& hstream, const HuffmanTa
         }
     }
 
-#if JPG_DEBUG
-    dbgln("If you're seeing this...the jpeg decoder needs to support more kinds of JPEGs!");
-#endif
+    dbgln_if(JPG_DEBUG, "If you're seeing this...the jpeg decoder needs to support more kinds of JPEGs!");
     return {};
 }