Unable to build the project using Ninja

[Michcioperz]

cmake -G Ninja -DCMAKE_BUILD_TYPE=Release .. proceeds fine, but ninja afterwards fails.

An example error message:

ninja: error: 'seccomp_project-prefix/lib/libseccomp.a', needed by 'src/sio2jail', missing and no known rule to make it

[teqwve]

It looks like this: https://cmake.org/pipermail/cmake/2015-April/060234.html should fix it.

[teqwve]

Fixed in 9abc744