Tighten up make clean

Now it doesn't remove debug_reg_printer.h anymore, which is part of the
repo so shouldn't be removed.

Makefile

@@ -91,7 +91,7 @@ chisel: $(REGISTERS_CHISEL)
 
 clean:
 	rm -f $(DRAFT).pdf *.aux $(DRAFT).toc $(DRAFT).log $(REGISTERS_TEX) \
-	    $(REGISTERS_TEX:=.inc) *.o *_no128.S *.h \
+	    $(REGISTERS_TEX:=.inc) *.o *_no128.S debug_defines.[ch] \
 	    $(DRAFT).hst $(DRAFT).pyg debug_defines.* *.scala \
 	    $(NOTES).pdf $(NOTES).toc $(NOTES).log $(NOTES).hst $(NOTES).pyg \
 	    *.idx *.ind *.ilg *.lot *.lof *.out