Make perlio line buffer VMS record-oriented files on output.

Make perlio line buffer VMS record-oriented files on output.

When perlio flushes down to the unix layer, it can introduce a
spurious record boundary when writing to a record-oriented file.
Perl may create such files when doing edit-in-place or any other
context where the file format is inherited from a previous
version of the file.

The problem can be eliminated by enabling line buffering on such
files when they are opened.  This was a regression in 5.10.0 since
before that stdio's buffering performed the same function.

N.B.  Lines longer than the size of the perlio buffer will still
result in multiple records -- a larger buffer may be necessary.

For more details and discussion see:

http://www.nntp.perl.org/group/perl.vmsperl/2010/11/msg15419.html

Thanks to Martin Zinser for the problem report.