Testsuite: Test cipher-suite driven downgrade.

The full suite is now run when the minimum protocol version
is SSL 3.0 for both client and server, and the maximum
protocol version is the same for client and server.

This allows testing of downgrading to older protocol
versions due to the only common cipher suite being
removed in the common protocol version.

Also shortens "expected" to "exp" in lots of places to get past the
m4 4096 byte limit.
No longer scratch area. Fixed Pike case.
Testsuite [ssl]: Fixed some special cases.

The certificates used by the testsuite don't support the
KE_dh_rsa and KE_ecdh_rsa suites in TLS 1.1 and earlier.
This means that the corresponding deprecated suites will
fail even after protocol version downgrade.

Fixes [LysLysKOM 21032408].
release number bumped to 8.0.24 by export.pike
release number bumped to 8.0.25 by export.pike
Don't spam the console with random data.
Avoid using %O for 8-bit strings.
F_APPEND_MAPPING: overwrite existing entries.

The new append mapping opcode did not overwrite existing entries in the
destructive case (when the mapping had only "1" reference).
Testsuite: very basic test of F_APPEND_MAPPING