Use initCause

Summary:
Retain any original error by making it the cause of the final `UnsatisfiedLinkError`.

The class does not have a constructor for a cause. So use `initCause`.

Reviewed By: MatthewLangille, simpleton

Differential Revision: D21134144

fbshipit-source-id: b1f56487617beef052e5c5b132d0a47a3353b582

java/com/facebook/soloader/SoLoader.java

@@ -893,7 +893,11 @@ private static void doLoadLibraryBySoName(
         sb.append(" result: ").append(result);
         final String message = sb.toString();
         Log.e(TAG, message);
-        throw new UnsatisfiedLinkError(message);
+        UnsatisfiedLinkError err = new UnsatisfiedLinkError(message);
+        if (error != null) {
+          err.initCause(error);
+        }
+        throw err;
       }
     }
   }