Replace C types by stdint.h types

Not all occurrences have been replaced, in some cases they have been
left as they were before (like in rgbgfx and when they are in the
interface of a C standard library function).

Signed-off-by: Antonio Niño Díaz <antonio_nd@outlook.com>

include/link/object.h

@@ -1,6 +1,6 @@
 #ifndef RGBDS_LINK_OBJECT_H
 #define RGBDS_LINK_OBJECT_H
 
-extern void obj_Readfile(char *tzObjectfile);
+void obj_Readfile(char *tzObjectfile);
 
 #endif