Simplify life for md5: include (slightly modified) md5.h and md5c.c

from RFC 1321 here, and point to that RFC instead of a non-existant
incompatible file on rsa.com.

Modules/md5.h

@@ -0,0 +1,69 @@
+/* MD5.H - header file for MD5C.C
+ */
+
+/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
+rights reserved.
+
+License to copy and use this software is granted provided that it
+is identified as the "RSA Data Security, Inc. MD5 Message-Digest
+Algorithm" in all material mentioning or referencing this software
+or this function.
+
+License is also granted to make and use derivative works provided
+that such works are identified as "derived from the RSA Data
+Security, Inc. MD5 Message-Digest Algorithm" in all material
+mentioning or referencing the derived work.
+
+RSA Data Security, Inc. makes no representations concerning either
+the merchantability of this software or the suitability of this
+software for any particular purpose. It is provided "as is"
+without express or implied warranty of any kind.
+
+These notices must be retained in any copies of any part of this
+documentation and/or software.
+ */
+
+/* ========== include global.h ========== */
+/* GLOBAL.H - RSAREF types and constants
+ */
+
+/* PROTOTYPES should be set to one if and only if the compiler supports
+  function argument prototyping.
+The following makes PROTOTYPES default to 0 if it has not already
+  been defined with C compiler flags.
+ */
+#ifndef PROTOTYPES
+#define PROTOTYPES 0
+#endif
+
+/* POINTER defines a generic pointer type */
+typedef unsigned char *POINTER;
+
+/* UINT2 defines a two byte word */
+typedef unsigned short int UINT2;
+
+/* UINT4 defines a four byte word */
+typedef unsigned long int UINT4;
+
+/* PROTO_LIST is defined depending on how PROTOTYPES is defined above.
+If using PROTOTYPES, then PROTO_LIST returns the list, otherwise it
+  returns an empty list.
+ */
+#if PROTOTYPES
+#define PROTO_LIST(list) list
+#else
+#define PROTO_LIST(list) ()
+#endif
+/* ========== End global.h; continue md5.h ========== */
+
+/* MD5 context. */
+typedef struct {
+  UINT4 state[4];                                   /* state (ABCD) */
+  UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
+  unsigned char buffer[64];                         /* input buffer */
+} MD5_CTX;
+
+void MD5Init PROTO_LIST ((MD5_CTX *));
+void MD5Update PROTO_LIST
+  ((MD5_CTX *, unsigned char *, unsigned int));
+void MD5Final PROTO_LIST ((unsigned char [16], MD5_CTX *));