ensure context exists when LinkState is created

kmaehashi · kmaehashi · commit aa7f10eee65c · 2018-06-20T19:39:10.000+09:00
This is needed as SimpleKernel may be invoked before calling any Runtime APIs.
diff --git a/cupy/cuda/function.pyx b/cupy/cuda/function.pyx
@@ -191,6 +191,7 @@ cdef class LinkState:
     """CUDA link state."""
 
     def __init__(self):
+        runtime._ensure_context()
         self.ptr = driver.linkCreate()
 
     def __del__(self):
