Fold dtls1_set_message_header into dtls1_set_handshake_header.

The frag_off/frag_len parameters are always zero, and the return value is never
used.

Change-Id: If7487b23c55f2a996e411b25b76a8e1651f25d8b
Reviewed-on: https://boringssl-review.googlesource.com/2601
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index 6d8276a..8522375 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -836,9 +836,8 @@
 int dtls1_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek);
 int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
 	unsigned int len);
-unsigned char *dtls1_set_message_header(SSL *s, 
-	unsigned char *p, unsigned char mt,	unsigned long len, 
-	unsigned long frag_off, unsigned long frag_len);
+void dtls1_set_message_header(SSL *s, uint8_t mt, unsigned long len,
+	unsigned short seq_num, unsigned long frag_off, unsigned long frag_len);
 
 int dtls1_write_app_data_bytes(SSL *s, int type, const void *buf, int len);
 int dtls1_write_bytes(SSL *s, int type, const void *buf, int len);