systemd-python: add missing check for return of PyDict_SetItem in _reader.c
systemd-analyze: free unit_times only if it is not NULL
manager: print p and then free it
systemctl: check if iterator was initialized succesfully
fstab-generator: initrd - mount selected entries from /sysroot/etc/fstab

We only mount "/usr" and entries marked with "x-initrd.mount".

This (together with the right unit files) is needed in the initramfs in order to
natively support mounting /usr (and friends) from the initramfs.

The way it is meant to work is:
 * wait for sysroot.mount to be mounted
 * do a daemon-reload to generate sysroot-usr.mount (++) from /sysroot/etc/fstab
 * wait for sysroot-usr.mount to be mounted
 * switch-root

Cc: Harald Hoyer <harald.hoyer@gmail.com>
Cc: Dave Reisner <d@falconindy.com>
initrd: add unit files needed for basic systemd-in-initrd support

This will:
 * mount all configured filesystems (typically the rootfs on /sysroot)
 * reload the configuration to pick up anything from the mounted fs (typically
   /sysroot/etc/fstab)
 * mount any newly configured filesystems (typically /usr on /sysroot/usr, if
   applicable)
 * shut-down and clean-up any daemons running in the initramfs (typically udevd)
 * switch-root to /sysroot and start the real init

For an example of what files should be included in an initramfs based on this
see
<https://mailman.archlinux.org/pipermail/arch-projects/2013-February/003628.html>.

Cc: Harald Hoyer <harald.hoyer@gmail.com>
Cc: Dave Reisner <d@falconindy.com>