ffmpeg may not build with SSH option turned on

[Mikhail T.]

Upstream's configure uses pkgconfig to look for libssh, but the port
asks merely for libssh.so. When the building system has only the libssh2
port installed, the dependency is satisfied, but ffmpeg's configure
breaks because pkgconfig can not find libssh.

Not sure, how to best fix this... Ideally, I guess, ffmpeg's configure
would check for libssh2 first and, failing that -- for libssh... Yours,

    -mi