Make the include guards consistent by renaming them systematically according
to the naming conventions below

The public header files (in the 'include/openssl' directory) are not changed
in 1.1.1, because it is a stable release.

For the private header files files, the guard names try to match the path
specified in the include directives, with all letters converted to upper case
and '/' and '.' replaced by '_'. An extra 'OSSL_' is added as prefix.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9681)

In light of potential UKS (unknown key share) attacks on some
applications, primarily browsers, despite RFC761, name checks are
by default applied with DANE-EE(3) TLSA records.  Applications for
which UKS is not a problem can optionally disable DANE-EE(3) name
checks via the new SSL_CTX_dane_set_flags() and friends.
Reviewed-by: NRich Salz <rsalz@openssl.org>

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

It is up to the caller of SSL_dane_tlsa_add() to take appropriate
action when no records are added successfully or adding some records
triggers an internal error (negative return value).

With this change the caller can continue with PKIX if desired when
none of the TLSA records are usable, or take some appropriate action
if DANE is required.

Also fixed the internal ssl_dane_dup() function to properly initialize
the TLSA RR stack in the target SSL handle.  Errors in ssl_dane_dup()
are no longer ignored.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Reviewed-by: NViktor Dukhovni <viktor@openssl.org>

Reviewed-by: NEmilia Käsper <emilia@openssl.org>

This was done by the following
        find . -name '*.[ch]' | /tmp/pl
where /tmp/pl is the following three-line script:
        print unless $. == 1 && m@/\* .*\.[ch] \*/@;
        close ARGV if eof; # Close file to reset $.

And then some hand-editing of other files.
Reviewed-by: NViktor Dukhovni <viktor@openssl.org>

Don't define stacks in C source files: it causes warnings
about unused functions in some compilers.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

Also tweak some of the code in demos/bio, to enable interactive
testing of BIO_s_accept's use of SSL_dup.  Changed the sconnect
client to authenticate the server, which now exercises the new
SSL_set1_host() function.
Reviewed-by: NRichard Levitte <levitte@openssl.org>