added #include <string.h> to fix these errors:

$ gcc -o telnetenable md5.c blowfish.c telnetenable.c
md5.c: In function ‘MD5Update’:
md5.c:75: warning: incompatible implicit declaration of built-in function ‘memmove’
md5.c:78: warning: incompatible implicit declaration of built-in function ‘memmove’
md5.c:86: warning: incompatible implicit declaration of built-in function ‘memmove’
md5.c:93: warning: incompatible implicit declaration of built-in function ‘memmove’
md5.c: In function ‘MD5Final’:
md5.c:113: warning: incompatible implicit declaration of built-in function ‘memset’
md5.c:119: warning: incompatible implicit declaration of built-in function ‘memset’
md5.c:129: warning: incompatible implicit declaration of built-in function ‘memmove’
md5.c:130: warning: incompatible implicit declaration of built-in function ‘memset’

md5.c

@@ -15,6 +15,7 @@
  * will fill a supplied 16-byte array with the digest.
  */
 
+#include <string.h>
 #include "md5.h"
 
 static void MD5Transform(unsigned int buf[4], unsigned int const in[16]);