Add CloseStdinAndStdout()

Add CloseStdinAndStdout().

There will be no reason to leave the handler process connected to its
invoker’s stdin or stdout.

On the other hand, I’m currently leaving it connected to the original
and stderr, as these may be useful for diagnostics.

R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/25c3afaac52cb5a63e00b60203bba142aaf4c0a4

[Mark Mentovai, 2014-12-18 23:20:41]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Mark Mentovai, 2014-12-18 23:20:42]

This was broken out from the handler, which is a work-in-progress at
https://codereview.chromium.org/798743003/. handler/mac/main.cc calls this
function.

[Robert Sesek, 2014-12-19 18:12:05]

LGTM

https://codereview.chromium.org/818573002/diff/1/util/posix/close_stdio.h
File util/posix/close_stdio.h (right):

https://codereview.chromium.org/818573002/diff/1/util/posix/close_stdio.h#new...
util/posix/close_stdio.h:20: //! \brief Closes `stdin` and `stdout` by opening
`/dev/null` over them.
It may be advisable to mention that is is only safe when single-threaded, or
when you have guarantees over the other threads in the process.

[Mark Mentovai, 2014-12-19 19:20:17]

Updated.

[Mark Mentovai, 2014-12-19 19:20:25]

Committed patchset #2 (id:20001) manually as
25c3afaac52cb5a63e00b60203bba142aaf4c0a4 (presubmit successful).