ortho and concentrate used together cause a crash

As discussed in https://forum.graphviz.org/t/dot-exe-no-longer-works/1501.

Input: 1501.gv

Command: dot -Tpng -Gcharset=Latin1 -o /dev/null 1501.gv

Result:

$ env UBSAN_OPTIONS=print_stacktrace=1 LD_LIBRARY_PATH=${PREFIX}/lib ${PREFIX}/bin/dot -Tpng -Gcharset=Latin1 -o /dev/null /tmp/1501.gv 
splines.c:222:12: runtime error: member access within null pointer of type 'struct Agobj_t'
    #0 0x7fbf2af4b59c  (/tmp/tmp.wvAJtj9vxt/lib+0x54b59c)
    #1 0x7fbf2af4c8f4  (/tmp/tmp.wvAJtj9vxt/lib+0x54c8f4)
    #2 0x7fbf2b0af403  (/tmp/tmp.wvAJtj9vxt/lib+0x6af403)
    #3 0x7fbf2b0b133a  (/tmp/tmp.wvAJtj9vxt/lib+0x6b133a)
    #4 0x7fbf25cb043a in _dot_splines /tmp/tmp.FpMlosEKrT/graphviz/lib/dotgen/dotsplines.c:291
    #5 0x7fbf25cba78b in dot_splines /tmp/tmp.FpMlosEKrT/graphviz/lib/dotgen/dotsplines.c:524
    #6 0x7fbf25c2f192 in dotLayout /tmp/tmp.FpMlosEKrT/graphviz/lib/dotgen/dotinit.c:320
    #7 0x7fbf25c327e5 in doDot /tmp/tmp.FpMlosEKrT/graphviz/lib/dotgen/dotinit.c:447
    #8 0x7fbf25c33124 in dot_layout /tmp/tmp.FpMlosEKrT/graphviz/lib/dotgen/dotinit.c:494
    #9 0x7fbf2ae41d19  (/tmp/tmp.wvAJtj9vxt/lib+0x441d19)
    #10 0x564764c9c72e in main /tmp/tmp.FpMlosEKrT/graphviz/cmd/dot/dot.c:89
    #11 0x7fbf29e29d8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
    #12 0x7fbf29e29e3f in __libc_start_main_impl ../csu/libc-start.c:392
    #13 0x564764c9c364 in _start (/tmp/tmp.wvAJtj9vxt/bin/dot+0x2364)