- Create per-arch unique distribution file names
- Source .gns3a information from /etc/os-release
Instead of attempting to create unique file names by hard-coding an
'infix-' prefix and extracting the "board" or "arch" part from the
defconfig, let's use the branding information from /etc/os-release
along with $BR2_ARCH.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>