Thanks to the required word alignment of the `switch` jump table in
TH05's dialog_op(), we do in fact have to slice dialog code into
exactly two* translation units. Three might have been better because we
would have only needed to compile this shared code once, but TH05 also
has one exclusive function in the area covered by this new shared
translation unit anyway. At least we can meaningfully share the actual
source files between games here.
* With an additional one at the end for now, because I absolutely had
to RE that EMS code in late 2021, but we'll catch up with that one in
the end.
Part of P0258, funded by [Anonymous] and Blue Bolt.
nmlgc