ffb34d2485
This commit fixes the build process for the documentation that was previously
unable to build separately via meson due to a dependency issue.
Previously, trying to build the API documentation via `ninja NetworkManager-doc`
failed due to missing dependencies (for example, `nm-dbus-types.xml` was not built).
I believe this happens due to some different handling of static paths vs. custom_target
by meson in this case.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1801
Fixes: 03637ad8b5 ('build: add initial support for meson build system')