[Packaging][C++] Plasma headers not included for ubuntu-xenial libplasma-dev debian package

[asfimport]

See https://github.com/kou/arrow/blob/master/dev/tasks/linux-packages/debian.ubuntu-xenial/libplasma-dev.install

Issue is still present on latest master branch, the debian install script is correct: https://github.com/kou/arrow/blob/master/dev/tasks/linux-packages/debian/libplasma-dev.install

The first line is missing from the ubuntu install script causing no headers to be installed when apt-get is used to install libplasma-dev.

Reporter: Wannes G
Assignee: Kouhei Sutou / @kou

PRs and other links:

• GitHub Pull Request #5050

_{Note: This issue was originally created as ARROW-6186. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 5050
#5050