The old proxy tests test the implementation of an application proxy
policy callback defined in the test itself, which is not particularly
useful.

It is, however, useful to test cert verify overrides in
general. Therefore, replace these tests with tests for cert verify
callback behaviour.

Also glob the ssl test inputs on the .in files to catch missing
generated files.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Reviewed-by: NRichard Levitte <levitte@openssl.org>

The simple reason is that the pre-generated files are mainly for Unix.
The VMS variants look slightly different, so comparing will always fail.
Reviewed-by: NEmilia Käsper <emilia@openssl.org>

Reviewed-by: NRichard Levitte <levitte@openssl.org>

Currently, SSL tests are configured via command-line switches to
ssltest.c. This results in a lot of duplication between ssltest.c and
apps, and a complex setup. ssltest.c is also simply old and needs
maintenance.

Instead, we already have a way to configure SSL servers and clients, so
we leverage that. SSL tests can now be configured from a configuration
file. Test servers and clients are configured using the standard
ssl_conf module. Additional test settings are configured via a test
configuration.

Moreover, since the CONF language involves unnecessary boilerplate, the
test conf itself is generated from a shorter Perl syntax.

The generated testcase files are checked in to the repo to make
it easier to verify that the intended test cases are in fact run; and to
simplify debugging failures.

To demonstrate the approach, min/max protocol tests are converted to the
new format. This change also fixes MinProtocol and MaxProtocol
handling. It was previously requested that an SSL_CTX have both the
server and client flags set for these commands; this clearly can never work.

Guide to this PR:
 - test/ssl_test.c - test framework
 - test/ssl_test_ctx.* - test configuration structure
 - test/handshake_helper.* - new SSL test handshaking code
 - test/ssl-tests/ - test configurations
 - test/generate_ssl_tests.pl - script for generating CONF-style test
   configurations from perl inputs
Reviewed-by: NRichard Levitte <levitte@openssl.org>