[C++] Write 0-length EOS indicator at end of stream

[asfimport]

While not required, this will make the C++ StreamWriter more consistent with the Java one

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

Related issues:

• Arrow 0.3 release (blocks)

_{Note: This issue was originally created as ARROW-910. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 614
#614