Link against internally defined libraries

[islas]

Neither #2595 nor #2758 fully addressed the underlying issue that final netcdf target linking was failing due to missing dependencies previously defined in other internal targets. While a valid solution to manually specify linking dependencies again, part of the effort is to make use of the target structure in cmake to further inform future linking.

The usage of the generator expression $<TARGET_OBJECTS:...> negates any target-specific linking that ought to be inherited to the netcdf target. To avoid this issue internal targets such as dispatch should be directly linked. Since target netcdf does not have PUBLIC/PRIVATE definitions for its linking, a compromise for now is to use the $<TARGET_NAME_IF_EXISTS:...> generator expression which will fully fix linking even prior to #2595 / #2758 and a valid config able to be found/imported by other cmake projects.

[islas]

@WardF Is there a good way to re-queue the tests? It looks like the Cygwin tests failed with some server request error - as far as I can tell not related to the code changes.

[WardF]

I've re-queued them and we will see what happens :)