Here, with the option --enable-threads and under cygwin, the ECL build fails when it tries to run ecl_min.exe. Here is the output:

[...]
cp /home/Gustavo/Gustavo/Downloads/ecl-9.12.3/src/../contrib/unicode/ucd.dat .
if [ -f CROSS-COMPILER ]; then \
                ./CROSS-COMPILER compile; \
        else \
                ECLDIR=`pwd`/ ./ecl_min compile; \
        fi

Internal or unrecoverable error in:
Got signal before environment was installed on our thread.
  [22: Invalid argument]
/bin/sh: line 4:  3456 Aborted                 (core dumped) ECLDIR=`pwd`/ ./ecl_min compile
make[1]: *** [bin/ecl.exe] Error 134
make[1]: Leaving directory `/cygdrive/c/Users/Gustavo/Downloads/ecl-9.12.3/build'
make: *** [all] Error 2


bash-3.2$ ./ecl_min.exe

Internal or unrecoverable error in:
Got signal before environment was installed on our thread.
  [22: Invalid argument]
Aborted (core dumped)