Removed additional exit constants definitions from cc65.h to stdlih.h. Guarded the definitions by #ifdef. Removed cc65.h includes from abort and assert implementations.

include/stdlib.h

@@ -48,6 +48,17 @@ typedef unsigned size_t;
 #define EXIT_SUCCESS    0
 #define EXIT_FAILURE    1
 
+#if __CC65_STD__ == __CC65_STD_CC65__
+
+/* Those non-standard cc65 exit constants definitions are in addition
+   to the EXIT_SUCCESS and EXIT_FAILURE constants, which should not be
+   redefined */ 
+#define EXIT_ASSERT 2
+#define EXIT_ABORT 3
+
+#endif
+
+
 /* Return type of the div function */
 typedef struct {
     int rem;