Implement md5c function, slower than Golang's implementation

keeping it in repo to make further improvements and also rename

        minio-hash ---> crypto

pkgs/crypto/md5c/md5.h

@@ -0,0 +1,43 @@
+/*
+ * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
+ * MD5 Message-Digest Algorithm (RFC 1321).
+ *
+ * Homepage:
+ * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
+ *
+ * Author:
+ * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
+ *
+ * This software was written by Alexander Peslyak in 2001.  No copyright is
+ * claimed, and the software is hereby placed in the public domain.
+ * In case this attempt to disclaim copyright and place the software in the
+ * public domain is deemed null and void, then the software is
+ * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
+ * general public under the following terms:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted.
+ *
+ * There's ABSOLUTELY NO WARRANTY, express or implied.
+ *
+ * See md5.c for more information.
+ */
+
+#ifndef __MD5_H__
+#define __MD5_H__
+
+/* Any 32-bit or wider unsigned integer data type will do */
+typedef unsigned int MD5_u32plus;
+
+typedef struct {
+	MD5_u32plus lo, hi;
+	MD5_u32plus a, b, c, d;
+	unsigned char buffer[64];
+	MD5_u32plus block[16];
+} MD5_CTX;
+
+extern void MD5_Init(MD5_CTX *ctx);
+extern void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size);
+extern void MD5_Final(unsigned char *result, MD5_CTX *ctx);
+
+#endif /* __MD5_H__ */