Add cm_cecit(). If the input file could not be opened, stop ngspice.

src/xspice/icm/analog/file_source/cfunc.mod

@@ -233,6 +233,7 @@ void cm_filesource(ARGS)   /* structure holding parms, inputs, outputs, etc.
             if (!loc->state->fp) {
                 cm_message_printf("cannot open file %s", PARAM(file));
                 loc->state->atend = 1;
+                cm_cexit(1);
             }
         }
         /* read, preprocess and store the data */

src/xspice/icm/table/table2D/cfunc.mod

@@ -732,6 +732,7 @@ EXITPOINT:
             free_local_data(loc);
             loc = (Table2_Data_t *) NULL;
         }
+        cm_cexit(1);
     }
     return loc;
 } /* end of function init_local_data */

src/xspice/icm/table/table3D/cfunc.mod

@@ -802,6 +802,7 @@ EXITPOINT:
             free_local_data(loc);
             loc = (Table3_Data_t *) NULL;
         }
+        cm_cexit(1);
     }
     return loc;
 } /* end of function init_local_data */