Merge #5394

5394: Tell what has to be changed in check_header_guards.py r=Jupeyy a=def-

Example:

Wrong header guard in src/game/bezier.h, is: #ifndef GAAME_BEZIER_H, should be: #ifndef GAME_BEZIER_H

<!-- What is the motivation for the changes of this pull request -->

## Checklist

- [ ] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: def <dennis@felsin9.de>

scripts/check_header_guards.py

@@ -23,14 +23,14 @@ def check_file(filename):
 				break
 			if line[0] == "/" or line[0] == "*" or line[0] == "\r" or line[0] == "\n" or line[0] == "\t":
 				continue
+			header_guard = "#ifndef " + ("_".join(filename.split(PATH)[1].split("/"))[:-2]).upper() + "_H"
 			if line.startswith("#ifndef"):
-				header_guard = "#ifndef " + ("_".join(filename.split(PATH)[1].split("/"))[:-2]).upper() + "_H"
 				if line[:-1] != header_guard:
 					error = True
-					print("Wrong header guard in {}".format(filename))
+					print("Wrong header guard in {}, is: {}, should be: {}".format(filename, line[:-1], header_guard))
 			else:
 				error = True
-				print("Missing header guard in {}".format(filename))
+				print("Missing header guard in {}, should be: {}".format(filename, header_guard))
 			break
 	return error