I got it working now.
If someone has to do the same, just create a new recipe for openssl 1.0.0 and copy libssl.so.1.0.0 and libcrypto.so.1.0.0 from an installed ubuntu (I know, it's not so nice)
Add this recipe as RDEPENDS to your libjabra recipe and to the application recipe, which uses libjabra.
Did any of you get a Yocto build with libjabra working?
I'm working right now on Yocto branch 'thud' and I'm struggling with the libssl and libcrypto (openssl) versions. thud still supports openssl10, but I only get the newest version (1.0.2) or with openssl (1.1) working.
Can anyone help me with this problem?