info: Fix outputting manpage to file

* info/info.c (info_session_or_dump_one_node):
New function, wrapping info_session_one_node.  Dump node to
output file if --output given or info output was piped.
(main): Call info_session_or_dump_one_node both for manpage nodes
and for "virtual index" nodes.

This fixes piping the output of 'info' when a manpage is loaded,
as in "info man | head".  Report from Arne Babenhauserheide.
1 file changed