Typedef ssl_early_callback_ctx to SSL_CLIENT_HELLO.

It's our ClientHello representation. May as well name it accordingly.
Also switch away from calling the variable name ctx as that conflicts
with SSL_CTX.

Change-Id: Iec0e597af37137270339e9754c6e08116198899e
Reviewed-on: https://boringssl-review.googlesource.com/12581
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

ssl/ssl_lib.c

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 8c1a300..7ac4016 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -1693,9 +1693,10 @@
 }
 
 STACK_OF(SSL_CIPHER) *
-    ssl_parse_client_cipher_list(const struct ssl_early_callback_ctx *ctx) {
+    ssl_parse_client_cipher_list(const SSL_CLIENT_HELLO *client_hello) {
   CBS cipher_suites;
-  CBS_init(&cipher_suites, ctx->cipher_suites, ctx->cipher_suites_len);
+  CBS_init(&cipher_suites, client_hello->cipher_suites,
+           client_hello->cipher_suites_len);
 
   STACK_OF(SSL_CIPHER) *sk = sk_SSL_CIPHER_new_null();
   if (sk == NULL) {
@@ -2843,13 +2844,13 @@
 
 int SSL_is_dtls(const SSL *ssl) { return ssl->method->is_dtls; }
 
-void SSL_CTX_set_select_certificate_cb(
-    SSL_CTX *ctx, int (*cb)(const struct ssl_early_callback_ctx *)) {
+void SSL_CTX_set_select_certificate_cb(SSL_CTX *ctx,
+                                       int (*cb)(const SSL_CLIENT_HELLO *)) {
   ctx->select_certificate_cb = cb;
 }
 
-void SSL_CTX_set_dos_protection_cb(
-    SSL_CTX *ctx, int (*cb)(const struct ssl_early_callback_ctx *)) {
+void SSL_CTX_set_dos_protection_cb(SSL_CTX *ctx,
+                                   int (*cb)(const SSL_CLIENT_HELLO *)) {
   ctx->dos_protection_cb = cb;
 }