[ptxdist] Globally define GIT_CEILING_DIRECTORIES?

["Sven Püschel" <s.pueschel@pengutronix.de>]

I would suggest globally setting the GIT_CEILING_DIRECTORIES environment 
variable when building packages.

Besides lshw, sockperf is now the second time I've encountered the 
buildsystem to check the current git repository. But as Git also checks 
the parent directories when searching for Git repositories, these checks 
may result in getting an unwanted Git repository (usually the BSP), 
resulting in package versions with a Git commit/version that has nothing 
to do with the actual package.

With GIT_CEILING_DIRECTORIES set to the parent directory of the 
extracted sources, Git will stop searching for parent Git repositories, 
when it encounters this directory. See my sockperf v2 patch for an 
example of using this environment variable.

Given this is a global change, does anyone see a potential problem?


Best regards

Sven