allow building python3 streaming on platforms without coroutines

Summary:
In order to use the Python 3 streaming thrift client on platforms that
don't support coroutines, conditionally define anything that depends
on coroutines.

Reviewed By: yfeldblum

Differential Revision: D21692900

fbshipit-source-id: 9f26d598097181ae43d1ff377a22b1c2f789321e

folly/python/async_generator.h

@@ -16,6 +16,10 @@
 
 #pragma once
 
+#include <folly/Portability.h>
+
+#if FOLLY_HAS_COROUTINES
+
 #include <folly/experimental/coro/AsyncGenerator.h>
 #include <folly/experimental/coro/Task.h>
 
@@ -42,3 +46,5 @@ class AsyncGeneratorWrapper {
 
 } // namespace python
 } // namespace folly
+
+#endif

folly/python/async_generator.pxd

@@ -14,7 +14,7 @@
 
 from folly.coro cimport cFollyCoroTask
 
-cdef extern from "folly/experimental/coro/AsyncGenerator.h" namespace "folly::coro":
+cdef extern from "folly/python/async_generator.h" namespace "folly::coro":
     cdef cppclass cAsyncGenerator "folly::coro::AsyncGenerator"[T]:
         pass
 

folly/python/coro.h

@@ -23,6 +23,10 @@
 
 #include <Python.h>
 #include <folly/Executor.h>
+#include <folly/Portability.h>
+
+#if FOLLY_HAS_COROUTINES
+
 #include <folly/experimental/coro/Task.h>
 #include <folly/python/AsyncioExecutor.h>
 #include <folly/python/executor.h>
@@ -58,3 +62,5 @@ void bridgeCoroTask(
 
 } // namespace python
 } // namespace folly
+
+#endif

folly/python/coro.pxd

@@ -15,7 +15,7 @@
 from cpython.ref cimport PyObject
 from folly cimport cFollyExecutor, cFollyTry
 
-cdef extern from "folly/experimental/coro/Task.h" namespace "folly::coro" nogil:
+cdef extern from "folly/python/coro.h" namespace "folly::coro" nogil:
     cdef cppclass cFollyCoroTask "folly::coro::Task"[T]:
         pass