Fix server-side KeyUpdates.

We sized the post-handshake message limit for the older zero-length
KeyUpdate and forgot to update it when it got larger.

Thanks to Matt Caswell for catching this.

Change-Id: I7d2189479e9516fbfb6c195dfa367794d383582c
Reviewed-on: https://boringssl-review.googlesource.com/13805
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index 336aa31..d6e984a 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -2290,7 +2290,16 @@
 			expectedError: ":WRONG_VERSION_NUMBER:",
 		},
 		{
-			name: "KeyUpdate",
+			name: "KeyUpdate-Client",
+			config: Config{
+				MaxVersion: VersionTLS13,
+			},
+			sendKeyUpdates:   1,
+			keyUpdateRequest: keyUpdateNotRequested,
+		},
+		{
+			testType: serverTest,
+			name:     "KeyUpdate-Server",
 			config: Config{
 				MaxVersion: VersionTLS13,
 			},