We want to reuse these generic DNS concepts in resolved hook
implementations, hence move them to shared code.
(This also enables us to immediately remove som SVCB record handling
duplicate definitions.)
No real code changes, just some moving around of things.
Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
For libsystemd's headers, the changes made depend on whether the
header is installed or not. For installed headers, the only change
made is that commonly included headers were moved to _sd-common.h.
For these headers, there should be no noticeable change in behavior
when including them. For non-installed headers, includes were replaced
with forward declarations where possible as usual.
Split out of #37344.
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Daan De Meyer
Ronan Pigott