ECL 21.2.1 fails to build on macOS 10.6 i386

An attempt to build ECL 21.2.1 had failed on macOS 10.6 i386 as:

Building ecl_min...

Internal or unrecoverable error in:
Got signal before environment was installed on our thread

;;; ECL C Backtrace
;;; 0   ecl_min                             0x00038c9b _ecl_dump_c_backtrace + 47
;;; 1   ecl_min                             0x0002cfc8 ecl_internal_error + 110
;;; 2   ecl_min                             0x0004fa0f deferred_signal_handler + 0
;;; 3   ecl_min                             0x0004f79d sigsegv_handler + 262
;;; 4   libSystem.B.dylib                   0x0025d05b _sigtramp + 43
;;; 5   ???                                 0xffffffff 0x0 + 4294967295
;;; 6   ecl_min                             0x00051db7 _ecl_sethash_pack + 66
;;; 7   ecl_min                             0x00007a97 cl_export2 + 579
;;; 8   ecl_min                             0x000042ef init_all_symbols + 431
;;; 9   ecl_min                             0x00004ba0 cl_boot + 1065
;;; 10  ecl_min                             0x00003a0e main + 33
;;; 11  ecl_min                             0x00003575 start + 53
/bin/sh: line 1: 76282 Abort trap              ECLDIR=`pwd`/ ./ecl_min compile
make[1]: *** [bin/ecl] Error 134

The whole build log available on MacPorts build bot: https://build.macports.org/builders/ports-10.6_i386-builder/builds/121655/steps/install-port/logs/stdio