[Bug preprocessor/59357] New: no documentation of #pragma once

[shawn at churchofgit dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59357

            Bug ID: 59357
           Summary: no documentation of #pragma once
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shawn at churchofgit dot com

Bug #11569 shows that #pragma once was de-deprecated, and very old cpp docs say
it is deprecated, but current docs don't even mention that it exists. e.g.
http://gcc.gnu.org/onlinedocs/cpp/Once_002dOnly-Headers.html
and http://gcc.gnu.org/onlinedocs/cpp/Pragmas.html