libssh: bump to 0.7.6 CVE-2018-10933 fix

libssh: bump to 0.7.6 CVE-2018-10933 fix

Bump from 0.7.5 to 0.7.6.  Upstream changelog:

Fixed CVE-2018-10933
Added support for OpenSSL 1.1
Added SHA256 support for ssh_get_publickey_hash()
Fixed config parsing
Fixed random memory corruption when importing pubkeys

Backported upstream patches since 0.7.6 to fix interactive
authentication issues amongst other things:

9d5cf209 libcrypto: Fix memory leak in evp_final()
10397321 gssapi: Set correct state after sending GSSAPI_RESPONSE (select mechanism OID)
7ad80ba1 server: Fix compile error
acb0e4f4 examples: Explicitly track auth state in samplesshd-kbdint
3fe7510b messages: Check that the requested service is 'ssh-connection'
734e3ce6 server: Set correct state after sending INFO_REQUEST (Kbd Interactive)
e4c6d591 packet: Add missing break in ssh_packet_incoming_filter()
f81ca616 misc: Add strndup implementation if not provides by the OS

Refresh patches.
Remove local backport for OpenSSL 1.1 support as is now in release
Remove PKG_INSTALL & CMAKE vars that are defaulted anyway
Add PKG_CPE_ID:=cpe:/a:libssh:libssh for CVE tracking
Remove BROKEN tag as is no longer broken

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>