Move PKCS# {1,5,8} functionality into separate files

This functionality fits better with src/tls (i.e., internal TLS
implementation), so move it there to make crypto_internal.c more
of a wrapper like other crypto_*.c files.

src/tls/pkcs5.h

@@ -0,0 +1,22 @@
+/*
+ * PKCS #5 (Password-based Encryption)
+ * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Alternatively, this software may be distributed under the terms of BSD
+ * license.
+ *
+ * See README and COPYING for more details.
+ */
+
+#ifndef PKCS5_H
+#define PKCS5_H
+
+u8 * pkcs5_decrypt(const u8 *enc_alg, size_t enc_alg_len,
+		   const u8 *enc_data, size_t enc_data_len,
+		   const char *passwd, size_t *data_len);
+
+#endif /* PKCS5_H */