Patch doesn't build for me against current trunk:

gcc -pthread -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes    -Werror=declaration-after-statement   -I. -IInclude -I./Include    -DPy_BUILD_CORE  -c ./Modules/_functoolsmodule.c -o Modules/_functoolsmodule.o
./Modules/_functoolsmodule.c: In function ‘infinite_lru_cache_wrapper’:
./Modules/_functoolsmodule.c:769:14: error: too few arguments to function ‘_PyDict_GetItem_KnownHash’
     result = _PyDict_GetItem_KnownHash(self->cache, key);
              ^
In file included from Include/Python.h:87:0,
                 from ./Modules/_functoolsmodule.c:2:
Include/dictobject.h:59:24: note: declared here
 PyAPI_FUNC(PyObject *) _PyDict_GetItem_KnownHash(PyObject *mp, PyObject *key,
                        ^
./Modules/_functoolsmodule.c:785:9: error: too few arguments to function ‘_PyDict_SetItem_KnownHash’
     if (_PyDict_SetItem_KnownHash(self->cache, key, result) < 0) {
         ^
In file included from Include/Python.h:87:0,
                 from ./Modules/_functoolsmodule.c:2:
Include/dictobject.h:71:17: note: declared here
 PyAPI_FUNC(int) _PyDict_SetItem_KnownHash(PyObject *mp, PyObject *key,
                 ^
Makefile:1695: recipe for target 'Modules/_functoolsmodule.o' failed
make: *** [Modules/_functoolsmodule.o] Error 1