Just build the stuff below, ideally doing "make spotless" before, then "make", "make install", "make check", in that order.

diff --git a/Makefile.cygwin b/Makefile.cygwin
index 5772caf..b4122ef 100644
--- a/Makefile.cygwin
+++ b/Makefile.cygwin
@@ -95,6 +95,7 @@ chicken-config.h: chicken-defaults.h
        echo "#define HAVE_LONG_LONG 1" >>$@
        echo "#define HAVE_MEMMOVE 1" >>$@
        echo "#define HAVE_MEMORY_H 1" >>$@
+       echo "#define HAVE_POSIX_POLL 1" >>$@
        echo "#define HAVE_SIGACTION 1" >>$@
        echo "#define HAVE_STDINT_H 1" >>$@
        echo "#define HAVE_STDLIB_H 1" >>$@