Document the info callback.

This callback is some combination of arguably useful stuff (bracket
handshakes, alerts) and completely insane things (find out when the
state machine advances). Deprecate the latter.

Change-Id: Ibea5b32cb360b767b0f45b302fd5f1fe17850593
Reviewed-on: https://boringssl-review.googlesource.com/6305
Reviewed-by: Adam Langley <alangley@gmail.com>

ssl/s3_clnt.c

diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index e34af59..242ac26 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -174,7 +174,7 @@
 
 int ssl3_connect(SSL *s) {
   BUF_MEM *buf = NULL;
-  void (*cb)(const SSL *ssl, int type, int val) = NULL;
+  void (*cb)(const SSL *ssl, int type, int value) = NULL;
   int ret = -1;
   int new_state, state, skip = 0;