Don't delete script.cpp after building (#1272)

Ensure consistency in linker script parser interface

Make the declaration and definition visible when compiling
so that the compiler can warn about inconsistencies.

Co-authored-by: ISSOtm <me@eldred.fr>

include/link/script.hpp

@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-
-// Parsing a linker script
-#ifndef RGBDS_LINK_SCRIPT_H
-#define RGBDS_LINK_SCRIPT_H
-
-#include <stdint.h>
-
-#include "linkdefs.hpp"
-
-/*
- * Parses the linker script, and modifies the sections mentioned within appropriately.
- */
-void script_ProcessScript(char const *path);
-
-#endif // RGBDS_LINK_SCRIPT_H