Suppress some BoringSSL test failures

The external BoringSSL tests had some failures as a result of
the extensions refactor. This was due to a deliberate relaxation
of the duplicate extensions checking code. We now only check
known extensions for duplicates. Unknown extensions are ignored.
This is allowed behaviour, so we suppress those BoringSSL tests.

Perl changes reviewed by Richard Levitte. Non-perl changes reviewed by Rich
Salz

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>