AC_C_BIGENDIAN
if test "x$ac_cv_c_bigendian" = "xyes"; then
    PHP_MONGODB_BUNDLED_CFLAGS="$PHP_MONGODB_BUNDLED_CFLAGS -DKMS_MESSAGE_BIG_ENDIAN=1 -DMONGOCRYPT_BIG_ENDIAN=1"
else
    PHP_MONGODB_BUNDLED_CFLAGS="$PHP_MONGODB_BUNDLED_CFLAGS -DKMS_MESSAGE_LITTLE_ENDIAN=1 -DMONGOCRYPT_LITTLE_ENDIAN=1"
fi