e.g. from 64-bit to 32-bit.
pybind11 is a header-only library, so there was no linking failure —
the only reason this ended up mattering was that it had some sort of
size check in it.
Fixes: 8a45e936ac ("libcamera: 0.2.0 → 0.3.0")
lttng-ust has a mandatory dependency on liburcu, which requires
architecture-specific code that isn't available for all platforms. To
enable building libcamera for those platforms, disable tracing support
if lttng-ust is unavailable. This fixes building libcamera for, for
example, loongarch64-linux.
The CI check complains about a new attribute introduced that's not using
the by-name pattern, even though it's using the same .nix file.
It seems using callPackage ../by-name/… from toplevel for the
alternative toplevel attribute seems to be others do this, so using the
same pattern here.
