Use mkdirp() in get_process_filename() (#4397)
Use mkdirp() in get_process_filename() (#4397)

Avoids race condition in case multiple i3 instances are started in parallel with e.g. systemd user units for multiple X(vfb) servers.
stapelberg/i3,Airblader/i3-original,i3/i3,Airblader/i3,i3/i3,stapelberg/i3,Airblader/i3-original,Airblader/i3,stapelberg/i3,i3/i3,stapelberg/i3,Airblader/i3-original,Airblader/i3,Airblader/i3-original,Airblader/i3-original,i3/i3,Airblader/i3