Since `_process_libs` appends the lib's dependencies this list already,
the final return value of `_process_libs` will end up after its
dependencies, which is the wrong way around. (The lib must come first,
then its dependencies)
The easiest solution is to simply pre-pend the return value of
`_process_libs` rather than appending it, so that its dependencies come
after the library itself.
Closes#4091.