bug #97501: The value of the D1500G macro of Ctape.h is wrong and affects LTO tapes

Corrected the prototype of the cvtden function.  I could not compile the
unittests directory Mac OS X because the prototype was using 'char *' instead
of the better 'const char *'.

h/Ctape_api.h

@@ -109,7 +109,7 @@ EXTERN_C int chkdirw       (char *);
 EXTERN_C int checkjobdied  (int[]);
 
 /* tape/cvtden.c       */
-EXTERN_C int cvtden        (char *);
+EXTERN_C int cvtden        (const char *const);
 
 /* tape/ebc2asc.c      */
 EXTERN_C void ebc2asc      (char *, int);

tape/cvtden.c

@@ -30,7 +30,7 @@ static char *adensc[CA_MAXDENNUM] = {
     "10GC",       "",       "",   "DDSC",  "20GC",  "25GC",  "35GC",  "50GC",  "40GC",   "60GC",
    "100GC",  "200GC",  "110GC",  "160GC", "300GC", "400GC", "500GC", "700GC", "800GC", "1000GC",
   "1500GC", "5000GC", "1600GC", "4000GC"};
-int cvtden(char	*aden)
+int cvtden(const char *const aden)
 {
 	int i;