strtok_r: remove useless casts

[Todd C. Miller]

There's no reason to cast delim to char * when we can just make
spanp const char * to match it.

 - todd

Index: lib/libc/string/strtok.c
===================================================================
RCS file: /cvs/src/lib/libc/string/strtok.c,v
retrieving revision 1.6
diff -u -p -u -r1.6 strtok.c
--- lib/libc/string/strtok.c    8 Aug 2005 08:05:37 -0000       1.6
+++ lib/libc/string/strtok.c    19 Jun 2015 15:09:13 -0000
@@ -40,11 +40,10 @@ strtok(char *s, const char *delim)
 char *
 strtok_r(char *s, const char *delim, char **last)
 {
-       char *spanp;
+       const char *spanp;
        int c, sc;
        char *tok;
 
-
        if (s == NULL && (s = *last) == NULL)
                return (NULL);
 
@@ -53,7 +52,7 @@ strtok_r(char *s, const char *delim, cha
         */
 cont:
        c = *s++;
-       for (spanp = (char *)delim; (sc = *spanp++) != 0;) {
+       for (spanp = delim; (sc = *spanp++) != 0;) {
                if (c == sc)
                        goto cont;
        }
@@ -70,13 +69,13 @@ cont:
         */
        for (;;) {
                c = *s++;
-               spanp = (char *)delim;
+               spanp = delim;
                do {
                        if ((sc = *spanp++) == c) {
                                if (c == 0)
                                        s = NULL;
                                else
-                                       s[-1] = 0;
+                                       s[-1] = '\0';
                                *last = s;
                                return (tok);
                        }