ril: import Oreo AOSP libril

Change-Id: I00750bad812dc263e9c74a504b48512a892376c8
diff --git a/ril/include/libril/ril_ex.h b/ril/include/libril/ril_ex.h
index 692e4df..ef59a70 100644
--- a/ril/include/libril/ril_ex.h
+++ b/ril/include/libril/ril_ex.h
@@ -22,6 +22,8 @@
 
 #define NUM_ELEMS_SOCKET(a)     (sizeof (a) / sizeof (a)[0])
 
+struct ril_event;
+
 void rilEventAddWakeup_helper(struct ril_event *ev);
 void listenCallback_helper(int fd, short flags, void *param);
 int blockingWrite_helper(int fd, void* data, size_t len);