Build pulls in both static and shared library of libwebsockets if available

[diizzyy]

If both variants are installed they're linked to ttyd which is incorrect. I couldn't find quick solution (time constraints) using the current layout so I used pkgconfig instead to pick up the correct library.

Link to pkgconfig variant, https://cgit.freebsd.org/ports/plain/sysutils/ttyd/files/patch-CMakeLists.txt

FreeBSD 13.1 / 13.2-BETA2
CMake: 3.25.1
libwebsockets: 4.3.2

[tsl0922]

https://github.com/warmcat/libwebsockets/blob/main/cmake/libwebsockets-config.cmake.in#L18
https://github.com/tsl0922/ttyd/blob/main/scripts/cross-build.sh#L88

It is set by upstream, I'm doing similar hack in ttyd's cross-build script too.