[Qbs] Include current git branch in installation directory

[Christian Gudrian]

Hi, Richard!

Thanks for your help.

Am 09.11.2018 um 13:49 schrieb richard at weickelt.de:
> I think You can use the Probe item for that purpose.

That would help to determine the current git branch. But how do I tell 
Qbs to prefix that branch to all installation paths? Neither 
qbs.installPrefix nor qbs.installRoot (which shouldn't be touched within 
qbs files anyway) can apparently be set globally at project level but 
only in the respective Group item.

Christian