tests: attempt to fix a conflict on port numbers
    
    ... where stunnel listens for legacy HTTPS and HTTP/2, which manifests
    as a hard-to-explain failure of the following tests: 1630 1631 1632 1904
    1941 1945 2050 2055 3028
    ```
    [...]
    startnew: perl -I../../tests ../../tests/secureserver.pl --pidfile ".https_server.pid" --logfile "log/https_stunnel.log" --ipv4 --proto https --stunnel "/usr/bin/stunnel" --srcdir "../../tests" --connect 42917 --accept 24642
    RUN: HTTPS server is PID 114398 port 24642
    * pid https => 114398 114402
    [...]
    startnew: perl -I../../tests ../../tests/secureserver.pl --pidfile ".https2_server.pid" --logfile "log/https2_stunnel.log" --id 2 --ipv4 --proto https --stunnel "/usr/bin/stunnel" --srcdir "../../tests" --connect 36763 --accept 24642
    startnew: child process has died, server might start up
    Warning: http2 server unexpectedly alive
    RUN: Process with pid 73992 signalled to die
    RUN: Process with pid 73992 forced to die with SIGKILL
    == Contents of files in the log/ dir after test 1630
    === Start of file http2_server.log
     14:01:21.881018 exit_signal_handler: 15
     14:01:21.881372 signalled to die
     14:01:21.881511 ========> IPv4 sws (port 36763 pid: 73992) exits with signal (15)
    === End of file http2_server.log
    === Start of file https2_stunnel.log
     [ ] Initializing inetd mode configuration
     [ ] Clients allowed=500
     [.] stunnel 5.69 on x86_64-redhat-linux-gnu platform
     [.] Compiled/running with OpenSSL 3.0.8 7 Feb 2023
     [.] Threading:PTHREAD Sockets:POLL,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI
     [ ] errno: (*__errno_location ())
     [ ] Initializing inetd mode configuration
     [.] Reading configuration from file /builddir/build/BUILD/curl-8.0.1/build-minimal/tests/https_stunnel.conf
     [.] UTF-8 byte order mark not detected
     [.] FIPS mode disabled
     [ ] Compression disabled
     [ ] No PRNG seeding was required
     [ ] Initializing service [curltest]
     [ ] Using the default TLS minimum version as specified in crypto policies. Not setting explicitly.
     [ ] Using the default TLS maximum version as specified in crypto policies. Not setting explicitly
     [ ] stunnel default security level set: 2
     [ ] Ciphers: PROFILE=SYSTEM
     [ ] TLSv1.3 ciphersuites: TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256
     [ ] TLS options: 0x2100000 (+0x0, -0x0)
     [ ] Session resumption enabled
     [ ] Loading certificate from file: /builddir/build/BUILD/curl-8.0.1/tests/stunnel.pem
     [ ] Certificate loaded from file: /builddir/build/BUILD/curl-8.0.1/tests/stunnel.pem
     [ ] Loading private key from file: /builddir/build/BUILD/curl-8.0.1/tests/stunnel.pem
     [ ] Private key loaded from file: /builddir/build/BUILD/curl-8.0.1/tests/stunnel.pem
     [ ] Private key check succeeded
     [!] No trusted certificates found
     [ ] DH initialization needed for DHE-RSA-AES256-GCM-SHA384
     [ ] DH initialization
     [ ] Could not load DH parameters from /builddir/build/BUILD/curl-8.0.1/tests/stunnel.pem
     [ ] Using dynamic DH parameters
     [ ] ECDH initialization
     [ ] ECDH initialized with curves X25519:P-256:X448:P-521:P-384
     [.] Configuration successful
     [ ] Deallocating deployed section defaults
     [ ] Binding service [curltest]
     [ ] Listening file descriptor created (FD=8)
     [ ] Setting accept socket options (FD=8)
     [ ] Option SO_REUSEADDR set on accept socket
     [.] Binding service [curltest] to 0.0.0.0:24642: Address already in use (98)
     [ ] Listening file descriptor created (FD=8)
     [ ] Setting accept socket options (FD=8)
     [ ] Option SO_REUSEADDR set on accept socket
     [.] Binding service [curltest] to :::24642: Address already in use (98)
     [!] Binding service [curltest] failed
     [ ] Unbinding service [curltest]
     [ ] Service [curltest] closed
     [ ] Deallocating deployed section defaults
     [ ] Deallocating section [curltest]
     [ ] Initializing inetd mode configuration
    === End of file https2_stunnel.log
    ```