message: mock: fix dereference before null check
  Pointer context has already been dereferenced when MemoryView created
diff: @@ -1028,7 +1028,7 @@ TEST_F(MockTest, C_API_AllocateDeviceMemory) {
  mem_flags.smHint = ISPCRT_SM_HOST_WRITE_DEVICE_READ;
  ISPCRTMemoryView mem = ispcrtNewMemoryViewForContext(context, buffer.data(), buffer.size(), &mem_flags);
  if (mem) ispcrtRelease(mem);
  - if (context) ispcrtRelease(context);
  + ispcrtRelease(context);
  ASSERT_EQ(sm_rt_error, ISPCRT_UNKNOWN_ERROR);
  }
  