[QBS] Support for GNU standards

[Andrzej Telszewski]

Hi,

From: /usr/share/qtcreator/qbs/share/qbs/modules/cpp/CppModule.qbs
I see that the following C/C++ standards are supported:

name: "cLanguageVersion"
allowedValues: ["c89", "c99", "c11"]

name: "cxxLanguageVersion"
allowedValues: ["c++98", "c++11", "c++14"]

What about the GUN variants, like "gnu99"?
For the moment I'm using cpp.commonCompilerFlags to specify the 
standard, but I wonder if the GNU variants are going to be supported 
through cLanguageVersion/cxxLanguageVersion ?

-- 
Best regards,
Andrzej Telszewski