deflate_compress: observe correct items in lazy compressor
deflate_compress: observe correct items in lazy compressor

Ensure that whenever deflate_choose_*() is called to choose a literal or
match, observe_*() is also called to tally it in the block split
statistics (except in deflate_compress_fastest(), which doesn't use the
block split statistics).  Previously, the lazy compressor contained an
optimization that made the block split statistics differ from the actual
lazy parse.  But that optimization no longer seems to be worthwhile.

ebiggers/libdeflate,ebiggers/libdeflate,ebiggers/libdeflate