Properly export ril_ex.h

Copying headers makes fixing compile errors hard, and breaks dependency
restrictions.  Move ril_ex.h to an exported include directory instead of
copying it.

Bug: 18903857
Change-Id: I4b59a01e442db0d3198def69a5a5ff17b2a41c66

ril/libril/Android.mk

@@ -43,9 +43,6 @@ LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/../include
 
 LOCAL_MODULE:= libril
 
-LOCAL_COPY_HEADERS_TO := libril
-LOCAL_COPY_HEADERS := ril_ex.h
-
 include $(BUILD_SHARED_LIBRARY)
 
 # For RdoServD which needs a static library

ril/libril/RilSocket.h

@@ -16,7 +16,7 @@
 
 #ifndef RIL_SOCKET_H_INCLUDED
 #define RIL_SOCKET_H_INCLUDED
-#include "ril_ex.h"
+#include <libril/ril_ex.h>
 #include "rilSocketQueue.h"
 #include <ril_event.h>