To get Chicken version 2.207 to compile with MinGW I had to change the line in configure that read
mingw_libdir=`mingw32-gcc -print-prog-name=ld | sed 's%/lib/gcc-lib/.*%/lib%'`
with
mingw_libdir=`mingw32-gcc -print-prog-name=ld | sed 's%/lib/gcc/.*%/lib%'`
and copy posixwin.c over posix.c and uposixwin.c over uposix.c.