*fix bug: stl file is closed twiced when reading ascii

Former-commit-id: f780fa35c9270f0e3b9789473f44e2b9d5ddd76c

include/igl/readSTL.cpp

@@ -187,7 +187,6 @@ IGL_INLINE bool igl::readSTL(
       }
     }
     // read endfacet
-    fclose(stl_file);
     goto close_true;
   }else
   {