Change existing build system for CFStream
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.cc b/src/core/lib/iomgr/ev_epoll1_linux.cc
index 3ebaf18..4b4c954 100644
--- a/src/core/lib/iomgr/ev_epoll1_linux.cc
+++ b/src/core/lib/iomgr/ev_epoll1_linux.cc
@@ -1237,7 +1237,7 @@
 }
 
 #else /* defined(GRPC_LINUX_EPOLL) */
-#if defined(GRPC_POSIX_SOCKET)
+#if defined(GRPC_POSIX_SOCKET_EV_EPOLL1)
 #include "src/core/lib/iomgr/ev_epoll1_linux.h"
 /* If GRPC_LINUX_EPOLL is not defined, it means epoll is not available. Return
  * NULL */