We previously used the Spicy plugin's `Spicy::available` to test for
Spicy support. However, having Spicy support does not necessarily mean that we
have built Zeek with its in-tree Spicy analyzers: the Spicy plugin
could have been pulled in from external. The new BIF now reliably
tells us whether the Spicy analyzers are available; its result
corresponds to what `zeek-config --have-spicy-analyzers` returns as
well.
We also move the two current checks over to use this BIF.
(Note: I refrained from renaming the CMake-side `USE_SPICY_ANALYERS`
to `HAVE_SPICY_ANALYZERS`. We should do this eventually for
consistency, but I didn't want to make more changes than necessary
right now.)
bc252c63dc