[libvirt] [PATCH 0/5] Some rearrangement & additions to pid file handling/locking

This series is a collection of changes related to pidfiles. First we define some wrappers around fcntl()'s lock file capability. Then all existing pidfile APIs from src/util/util.h are moved into a new file src/util/virpidfile.h. Next a new API for doing a sanity check on a PID (using /proc/$PID/exe) is introduced. Then two clever functions for doing race free, crash-safe acquisition & release of pidfiles are introduced. Finally libvirtd is converted to use the new pidfile acquisition API.