Build error on Raspbian Buster

[Dave Richards]

When I build --with-dffi=included everything builds fine.  When I build
--with-dffi=system I get the following build error: (sorry for those escape
sequences, not sure why they are there, I bet there is some colorization
going on somewhere, which is ironic since I am blind and it doesn't help me
a bit).

dpp: /home/pi/ecl.git/src/c/ffi.d -> ffi.o.c
/home/pi/ecl.git/src/c/ffi.d:218:4: error:
'ffi_type_complex_float' undeclared here (not in a
function); did you mean 'si_complex_float'?
   &ffi_type_complex_float,      /*@':csfloat',*/
    ^~~~~~~~~~~~~~~~~~~~~~
    si_complex_float
/home/pi/ecl.git/src/c/ffi.d:219:4: error:
'ffi_type_complex_double' undeclared here (not in a
function); did you mean 'ffi_type_longdouble'?
   &ffi_type_complex_double,     /*@':cdfloat',*/
    ^~~~~~~~~~~~~~~~~~~~~~~
    ffi_type_longdouble
/home/pi/ecl.git/src/c/ffi.d:220:4: error:
'ffi_type_complex_longdouble' undeclared here (not in a
function); did you mean 'ffi_type_longdouble'?
   &ffi_type_complex_longdouble, /*@':clfloat',*/
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
    ffi_type_longdouble
make[2]: *** [Makefile:88: ffi.o] Error 1
make[2]: Leaving directory '/home/pi/ecl.git/build/c'
make[1]: *** [Makefile:144: libeclmin.a] Error 2
make[1]: Leaving directory '/home/pi/ecl.git/build'
make: *** [Makefile:65: all] Error 2