Run the chain verify callback example in CI

The example needs --enable-chain-verify-cb, which the tls profile did not
carry, so client-tls-chainverifycb built as the stub that prints "wolfSSL
was built without --enable-chain-verify-cb" and nothing ran it. Add the
flag, and a pair entry that runs it against server-tls.

The flag only defines WOLFSSL_CHAIN_VERIFY_CB. WOLFSSL_ASYNC_IO is already
on in this profile, so nothing else in tls/ is affected.

server-tls presents ../certs/server-cert.pem on port 11111, which the
client's default anchor ../certs/ca-cert.pem issued, so the pair needs no
arguments beyond the host.

.github/examples-manifest.yml

@@ -131,7 +131,8 @@ profiles:
     flags: >-
       --enable-tls13 --enable-ech --enable-writedup --enable-pkcallbacks
       --enable-postauth --enable-cryptocb --enable-opensslall --enable-session-ticket
-      --enable-earlydata --enable-keygen --enable-des3 --enable-static --enable-shared
+      --enable-earlydata --enable-keygen --enable-des3 --enable-chain-verify-cb
+      --enable-static --enable-shared
     cflags: "-DHAVE_SECRET_CALLBACK"
 
   dtls:
@@ -955,6 +956,13 @@ examples:
           stdin: "hello\nshutdown\n"
           server_exit: killed
         expect: "Successful resume"
+      # Sends a fixed message rather than reading stdin, so no stdin here and
+      # the server never sees "shutdown".
+      - pair:
+          server: [./server-tls]
+          client: [./client-tls-chainverifycb, 127.0.0.1]
+          server_exit: killed
+        expect: "server: I hear ya fa shizzle"
     # Deliberately not run: client-ech (external crypto.cloudflare.com:443),
     # {client,server}-tls-uart (needs /dev/ttyUSB0), and the four *-perf
     # benchmarks. All still build.