Added enum for cc65 exit codes. replaced stdlib exit code names constants in libsrc with cc65 exit code named constants

include/cc65.h

@@ -36,6 +36,12 @@
 #ifndef _CC65_H
 #define _CC65_H
 
+typedef enum {
+    CC65_EXIT_SUCCESS,
+    CC65_EXIT_FAILURE,
+    CC65_EXIT_AFAILED,
+    CC65_EXIT_ABORT
+} cc65_exit_codes_t;
 
 
 /*****************************************************************************/