warning fix for #if CRASHREPORT

Thinko in the reformatting, not triggered during testing because I was
using !CRASHREPORT.  With it enabled, setting a watchpoint in gdb on
something unrelated resulted in nethack going into crashreport_init()
and never caming out.  (I imagine that it would have eventually but 10
or 15 minutes with nothing noticeable taking place was unbearable, and
the program hadn't even really started yet.)

src/end.c

@@ -413,7 +413,7 @@ submit_web_report(const char *msg, char *why)
         if (pid == 0) {
             char err[100];
 
-            (int) execve(CRASHREPORT, (char * const *) xargv, environ);
+            (void) execve(CRASHREPORT, (char * const *) xargv, environ);
             Sprintf(err, "Can't start " CRASHREPORT ": %s", strerror(errno));
             raw_print(err);
         } else {