Simplify fragmented HelloRequest state.

With server-side renegotiation gone, handshake_fragment's only purpose
in life is to handle a fragmented HelloRequest (we probably do need to
support those if some server does 1/n-1 record-splitting on handshake
records). The logic to route the data into
ssl3_read_bytes(SSL3_RT_HANDSHAKE) never happens, and the contents are
always a HelloRequest prefix.

This also trims a tiny bit of per-connection state.

Change-Id: Ia1b0dda5b7e79d817c28da1478640977891ebc97
Reviewed-on: https://boringssl-review.googlesource.com/6641
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 885dea2..f4b9535 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -3949,10 +3949,9 @@
 
   SSL3_RECORD rrec; /* each decoded record goes in here */
 
-  /* storage for Handshake protocol data received but not yet processed by
-   * ssl3_read_bytes: */
-  uint8_t handshake_fragment[4];
-  unsigned int handshake_fragment_len;
+  /* hello_request_len is the number of bytes of HelloRequest received, possibly
+   * split over multiple records. */
+  uint8_t hello_request_len;
 
   /* partial write - check the numbers match */
   unsigned int wnum; /* number of bytes sent so far */