xstrdup() not called anywhere in source. Removed.

advent.h

@@ -89,7 +89,6 @@ extern bool oldstyle, editline, prompt;
 #define READ_MODE "rb"
 #define WRITE_MODE "wb"
 extern void* xmalloc(size_t size);
-extern char* xstrdup(const char*);
 extern void packed_to_token(long, char token[]);
 extern void token_to_packed(char token[], long*);
 extern void vspeak(const char*, va_list);

misc.c

@@ -21,16 +21,6 @@ void* xmalloc(size_t size)
     return (ptr);
 }
 
-char* xstrdup(const char* s)
-{
-    char* ptr = strdup(s);
-    if (ptr == NULL) {
-        fprintf(stderr, "Out of memory!\n");
-        exit(EXIT_FAILURE);
-    }
-    return (ptr);
-}
-
 void packed_to_token(long packed, char token[6])
 {
     // Unpack and map back to ASCII.