ULTIMA1: Do not bundle ultima*.dat files with it

[mikrosk]

As discussed on discord: ultima1 is the only game not marked as 16-bit. However even that one requires bundling the huge .dat file because they are generic to the ultima engine:

ifdef ENABLE_ULTIMA
DIST_FILES_ENGINEDATA+=ultima.dat
DIST_FILES_ENGINEDATA+=ultima8.dat
endif

According to @ccawley2011:

Ultima I does need ultima.dat, but only for two tiny black and white bitmaps extracted from the original executable.
We do have an XBM decoder, so we could potentially use that to embed both of them in the executable, avoiding the need for ultima.dat if only Ultima 1 is enabled.