Switch the ssl_write_bytes hook to ssl_write_app_data.

The SSL_PROTOCOL_METHOD table needs work, but this makes it clearer
exactly what the shared interface between the upper later and TLS/DTLS
is.

BUG=468889

Change-Id: I38931c484aa4ab3f77964d708d38bfd349fac293
Reviewed-on: https://boringssl-review.googlesource.com/4955
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c
index c08455a..d898cf2 100644
--- a/ssl/s3_pkt.c
+++ b/ssl/s3_pkt.c
@@ -398,6 +398,10 @@
   return ret;
 }
 
+int ssl3_write_app_data(SSL *ssl, const void *buf, int len) {
+  return ssl3_write_bytes(ssl, SSL3_RT_APPLICATION_DATA, buf, len);
+}
+
 /* Call this to write data in records of type |type|. It will return <= 0 if
  * not all data has been sent or non-blocking IO. */
 int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len) {