[Bugfix] Fix failed attempt to open proc files while lacking permission.

[goddessfreya]

When started in the tty, powerline9k tries to open the stat file of the login process. Because the login process belongs to root, it's existence is hidden from non-privileged users. This will result in an error like __p9k_detect_terminal:27: no such file or directory: /proc/3434/stat.

Like #1336, this error appears to be ultimately harmless, but never the less annoying.

Signed-off-by: Hal Gentz [email protected]

[goddessfreya]

ping @dritter