Add generated biji-marshalers.h to libbiji dependency sources

The meson manual states that

Each target that depends on a generated header should add that header to it's sources, as seen above with libfoo and myexe. This is because there is no way for Meson or the backend to know that myexe depends on foo.h just because libfoo does, it could be a private header.

Since biji-marshalers.h is included by the libbiji public header libbiji.h, it must be added as a source to all targets that depend on libbiji. This can be done by adding it to the sources of libbiji_dep.

Fixes #157 (closed).