Panic if os-relase file contains comments

[abbbi]

seems to panic on SLES16:

panic: runtime error: index out of range [1] with length 1
 
goroutine 1 [running]:
github.com/wille/osutil.getOSRelease()
        /home/abi/go/pkg/mod/github.com/wille/osutil@v0.0.0-20201124133013-e7a03eb09286/dist_linux.go:80 +0x17c
github.com/wille/osutil.GetDist()
        /home/abi/go/pkg/mod/github.com/wille/osutil@v0.0.0-20201124133013-e7a03eb09286/dist_linux.go:105 +0x158

[abbbi]

problem is that the os-release file can contian comments:

cat /etc/os-release 
# The NAME and PRETTY_NAME fields have been chosen to state compatibility between our products.
# The use of "SLES" and "SUSE Linux Enterprise" rather than a more generic name is due to backward compatibility with existing OS detection code in applications of third party vendors.