When compiling with the UFST fontrasterizer and printing attached testfile
(selecting lineprinter font) and printing the '?' character a ' ' (space) is
printed instead. When using AFS it is printed correctly.

Caused by this piece of code in pctext.c :: get_next_char()

    if (plfont->storage == pcds_internal && chr == 0x0020) {
        *pis_space = true;
        *pchr = 0xffff;
        return 0;
     }

    /* check if the character is in the font and get the character
       width at the same time */

I.e. pl_map_symbol(...) returned (chr = 32)
the '?' has key=32 in the pl_map_m2u[] (With AFS the pl_map_symbol() skips the
pl_map_Unicode_to_MSL() because of is_MSL == 0 (with UFST is_MSL == 1).
pl_load_ufst_lineprinter() in plulfont.c sets the lineprinterfont to be MSL.