[haikuporter] Allow for custom licenses

[georgewhite]

Currently haikuporter does not allow for custom licenses.

For example, Scintilla has a custom license, which isn't compatible with other licenses on the list.

[waddlesplash]

1. This is the wrong place to report bugs in HaikuPorter, please do that at ​https://bitbucket.org/haikuports/haikuporter
2. This ticket is invalid anyway, HaikuPorter supports custom licenses.

If someone with modify permissions can please close this ticket as invalid...

[pulkomandy]

And here's how to do it, even:

• Next to your recipe you create a "licenses" folder and put the license as a text file into it (no .txt extension)
• You use the file name of that license as your LICENSE tag

In that case the license is included in the package so it is visible at the correct place in /boot/system/data/licenses when the package is installed. This is where we also provide the text for the "standard" licenses in the default system so not every package need to carry a copy of it.

Make sure your license is reasonably named, for example use the name from the SPDX list: ​http://spdx.org/licenses/ . If it is a "custom" license then use the name of the package.