datrie build error in python nightly (on travis-ci)

[sarnold]

check out what the upstream devs did, try the "fix":

  creating build/temp.linux-x86_64-3.10
  creating build/temp.linux-x86_64-3.10/src
  gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -fPIC -I/usr/include/datrie -I/home/travis/build/freepn/fpnd/.tox/py310/include -I/opt/python/3.10-dev/include/python3.10 -c src/cdatrie.c -o build/temp.linux-x86_64-3.10/src/cdatrie.o
  gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -fPIC -I/usr/include/datrie -I/home/travis/build/freepn/fpnd/.tox/py310/include -I/opt/python/3.10-dev/include/python3.10 -c src/datrie.c -o build/temp.linux-x86_64-3.10/src/datrie.o
  src/datrie.c: In function ‘__Pyx_PyList_Append’:
  src/datrie.c:1789:23: error: lvalue required as left operand of assignment
           Py_SIZE(list) = len+1;
                         ^
  src/datrie.c: In function ‘__Pyx_ListComp_Append’:
  src/datrie.c:1816:23: error: lvalue required as left operand of assignment
           Py_SIZE(list) = len+1;
                         ^