Makefile.mingw corrections and made the code pass much stricter checks (now mandated by Makefile.mignw) to ensure GCC 14 readiness.

src/codegen/codegen_accumulate.h

@@ -9,4 +9,4 @@ struct ir_data_t;
 
 void codegen_accumulate(int acc_reg, int delta);
 void codegen_accumulate_flush(void);
-void codegen_accumulate_reset();
+void codegen_accumulate_reset(void);