thrift/lib/py/protocol/fastproto.cpp: suppress llvm-19-exposed -Wcast-function-type-mismatch warnings

Summary:
This unblocks the llvm19 build of fb-smcc: D71070914
This avoids the following errors:

  thrift/lib/py/protocol/fastproto.cpp:1192:16: error: cast from 'PyObject *(*)(PyObject *, PyObject *, PyObject *)' (aka '_object *(*)(_object *, _object *, _object *)') to 'PyCFunction' (aka '_object *(*)(_object *, _object *)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
  thrift/lib/py/protocol/fastproto.cpp:1193:16: error: cast from 'PyObject *(*)(PyObject *, PyObject *, PyObject *)' (aka '_object *(*)(_object *, _object *, _object *)') to 'PyCFunction' (aka '_object *(*)(_object *, _object *)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]

Reviewed By: dtolnay

Differential Revision: D71121409

fbshipit-source-id: 6e68a6105b1a00b9a043a879f329cea27038a514

Author: Jim Meyering

third-party/thrift/src/thrift/lib/py/protocol/fastproto.cpp

@@ -1187,13 +1187,16 @@ static PyObject* decode(PyObject* /*self*/, PyObject* args, PyObject* kws) {
 
 /* -- PYTHON MODULE SETUP STUFF --- */
 
+FOLLY_PUSH_WARNING
+FOLLY_GNU_DISABLE_WARNING("-Wcast-function-type-mismatch")
 static PyMethodDef ThriftFastProtoMethods[] = {
 
     {"encode", (PyCFunction)encode, METH_VARARGS | METH_KEYWORDS, ""},
     {"decode", (PyCFunction)decode, METH_VARARGS | METH_KEYWORDS, ""},
 
     {nullptr, nullptr, 0, nullptr} /* Sentinel */
 };
+FOLLY_POP_WARNING
 
 extern "C" {
 struct module_state {