Activate Linux and/or MacOS-build for BIRT Report Designer

In the official BIRT-Releases, the standalone Birt RCP Report Designer is provided only for the windows environment. One might wonder the reasoning behind this decision.

We are going to change this.

There are two POM-Files where additional environments may be defined:
The Project’s Root-POM
The POM in build/birt-packages/birt-runtime-osgi

Add the following to the Maven-Tycho-Plugin (Linux, MacOS):

<environment>
  <os>linux</os>
  <ws>gtk</ws>
  <arch>x86_64</arch>
</environment>

<environment>
  <os>macosx</os>
  <ws>cocoa</ws>
  <arch>x86_64</arch>
</environment>