Move system/core/ off NO_ERROR.

It causes trouble for Windows, and OK already exists.

Bug: N/A
Test: builds
Change-Id: Ida22fd658b0ebb259c710ba39049b07c9e495d9c
diff --git a/gatekeeperd/gatekeeperd.cpp b/gatekeeperd/gatekeeperd.cpp
index 5f3ce36..f2818f3 100644
--- a/gatekeeperd/gatekeeperd.cpp
+++ b/gatekeeperd/gatekeeperd.cpp
@@ -386,7 +386,7 @@
             write(fd, result, strlen(result) + 1);
         }
 
-        return NO_ERROR;
+        return OK;
     }
 
 private: