Fix a memory leak in cxsparse.cc

Thanks to Alexander Mordvintsev for reporting it.

Change-Id: Ia872be42ce80209e46722fc16a928496cf97e256
diff --git a/internal/ceres/cxsparse.h b/internal/ceres/cxsparse.h
index d3b64fc..dd5eadc 100644
--- a/internal/ceres/cxsparse.h
+++ b/internal/ceres/cxsparse.h
@@ -72,9 +72,8 @@
   // The returned matrix should be deallocated with Free when not used anymore.
   cs_dis* AnalyzeCholesky(cs_di* A);
 
-  // Deallocates the memory of a matrix obtained from AnalyzeCholesky.
-  void Free(cs_di* factor);
-  void Free(cs_dis* factor);
+  void Free(cs_di* sparse_matrix);
+  void Free(cs_dis* symbolic_factorization);
 
  private:
   // Cached scratch space