Be strict about requiring ServerKeyExchange.

Missing ServerKeyExchange is handled, but only because it hits an
ERR_R_INTERNAL_ERROR in ssl3_send_client_key_exchange in trying to find the
server ECDH parameters. Be strict about requiring it for ECDHE.

Change-Id: Ifce5b73c8bd14746b8a2185f479d550e9e3f84df
Reviewed-on: https://boringssl-review.googlesource.com/1157
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index 328807a..ffa35db 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -359,6 +359,10 @@
 	// Certificate message is sent and no signature is added to
 	// ServerKeyExchange.
 	UnauthenticatedECDH bool
+
+	// SkipServerKeyExchange causes the server to skip sending
+	// ServerKeyExchange messages.
+	SkipServerKeyExchange bool
 }
 
 func (c *Config) serverInit() {