Provide RECORD_LAYER_set_data function

Reviewed-by: Richard Levitte <levitte@openssl.org>

ssl/record/ssl3_buffer.c

@@ -111,7 +111,7 @@
 
 #include "../ssl_locl.h"
 
-void SSL3_BUFFER_set_data(SSL3_BUFFER *b, unsigned char *d, int n)
+void SSL3_BUFFER_set_data(SSL3_BUFFER *b, const unsigned char *d, int n)
 {
     if(d != NULL)
         memcpy(b->buf, d, n);