Cygwin `make` gives an "unknown platform" error

I am running on Windows 7 64 bit using Cygwin.

I receive the following error:

gcc -O2 -DNDEBUG -falign-functions -Wall -Wno-strict-aliasing -Illt  -DUSE_COMPUTED_GOTO -c flisp.c -o flisp.o
In file included from llt/llt.h:5,
                 from flisp.c:46:
llt/dtypes.h:29:4: #error "unknown platform"
llt/dtypes.h:42:4: #error "__SIZEOF_POINTER__ undefined"
llt/dtypes.h:49:4: #error "this is one weird machine"
llt/dtypes.h:90:4: #error "unknown platform"
In file included from flisp.c:744:
read.c: In function `nextchar':
read.c:122: warning: array subscript has type `char'
read.c: In function `read_token':
read.c:162: warning: array subscript has type `char'
read.c: In function `peek':
read.c:260: warning: array subscript has type `char'
Makefile:25: recipe for target `flisp.o' failed
make: *** [flisp.o] Error 1

This seems to be because the __SIZEOF_POINTER__ constant is not defined.

I would like to take a stab at making this work, but I'm curious: what I will need to change within the dtypes.h file?

As an aside, Cygwin's pointer sizes are:

        Cygwin   Windows  Cygwin
        Linux    x86_64   Linux
        Windows           x86_64
        i686

sizeof(int)         4        4        4
sizeof(long)        4        4        8
sizeof(size_t)      4        8        8
sizeof(void*)       4        8        8

[digital-carver]

Under Cygwin, gcc defines macros __CYGWIN__ and __unix__, for use in platform checks. __CYGWIN__ is probably the one to use in the conditional at line 20 here. The ENDIAN macros seem to be defined as __ORDER_LITTLE_ENDIAN__, etc. on Cygwin. I've made a gist with the output of gcc -dM -E - <<<'' (which lists all predefined macros) here, run on Cygwin 2.10.0 x86_64 with gcc 6.4.0. __SIZEOF_POINTER__ does seem predefined here - perhaps it was introduced in the meantime.