toplev.c: set FILE * globals to NULL after fclose

gcc/ChangeLog:
	* toplev.c (finalize): Set aux_info_file, asm_out_file, and
	stack_usage_file to NULL after fclose calls.

From-SVN: r239322

gcc/ChangeLog

+2016-08-10  David Malcolm  <dmalcolm@redhat.com>
+
+	* toplev.c (finalize): Set aux_info_file, asm_out_file, and
+	stack_usage_file to NULL after fclose calls.
+
 2016-08-10  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
 	PR target/71873

gcc/toplev.c

@@ -1894,6 +1894,7 @@ finalize (bool no_backend)
   if (flag_gen_aux_info)
     {
       fclose (aux_info_file);
+      aux_info_file = NULL;
       if (seen_error ())
 	unlink (aux_info_file_name);
     }
@@ -1908,10 +1909,14 @@ finalize (bool no_backend)
 	fatal_error (input_location, "error writing to %s: %m", asm_file_name);
       if (fclose (asm_out_file) != 0)
 	fatal_error (input_location, "error closing %s: %m", asm_file_name);
+      asm_out_file = NULL;
     }
 
   if (stack_usage_file)
-    fclose (stack_usage_file);
+    {
+      fclose (stack_usage_file);
+      stack_usage_file = NULL;
+    }
 
   if (!no_backend)
     {