It turns out that Windows 2000 and ME will load icons with a greater color depth than 4 bits, but will only display them in 4-bit color. This is very ugly, so the new icons will only be used for Windows XP and newer.
printf("\n*** 'audiofile-config--version' returned %d.%d.%d, but the minimum version\n", $audiofile_major_version, $audiofile_minor_version, $audiofile_micro_version);
printf("*** of the Audio File Library required is %d.%d.%d. If audiofile-config is correct, then it is\n", major, minor, micro);
printf("*** best to upgrade to the required version.\n");
printf("*** If audiofile-config was wrong, set the environment variable AUDIOFILE_CONFIG\n");
printf("*** to point to the correct copy of audiofile-config, and remove the file\n");
printf("*** config.cache before re-running configure\n");