Fix failure with pragma once where buffer is NULL and buffer_valid is true.

PR preprocessor/24202
* files.c (_cpp_pop_file_buffer): Set buffer_valid to false.

From-SVN: r106472

libcpp/ChangeLog

+2005-11-03  James E Wilson  <wilson@specifix.com>
+
+	PR preprocessor/24202
+	* files.c (_cpp_pop_file_buffer): Set buffer_valid to false.
+
 2005-11-04  Joseph S. Myers  <joseph@codesourcery.com>
 
 	* include/cpplib.h (struct cpp_callbacks): Make error take

libcpp/files.c

@@ -1143,6 +1143,7 @@ _cpp_pop_file_buffer (cpp_reader *pfile, _cpp_file *file)
     {
       free ((void *) file->buffer);
       file->buffer = NULL;
+      file->buffer_valid = false;
     }
 }