man: Fix XDG_RUNTIME_DIR variable reference.
build-sys: Clarify some systemd sub-component variable/define names.

In newer versions of systemd some libraries were combined for the sake of
general simplicity.

This change checks against the newer name first and avoids separate pkgconfig
checks if it's found. We probably want to keep support for the older library
names for some time. systemd does allow for the shipping of compatibility
pkgconfig files to not break downstream code like ourselves which is why this
likely hasn't been "fixed" until now.

With this change we no longer rely on systemd having been built with those
compatibility pkgconfig files.
build-sys: Add support for newer systemd without compatibility libs

When systemd is built without compatibility libs, we only need to do one
pkgconfig check (libsystemd) rather than for libsystemd-login and
libsystemd-journal separately.

This change should allow building with both older and newer versions of
systemd.
socket-server: Add support for systemd socket activation.

This adds support to module-native-protocol-unix to take over already
listening sockets passed in via socket activation (e.g. from systemd)

Most of the code is isolated to socket-server but some cleanup code also
had to be tweaked to ensure we do not overzealously close open fds.
launch: Avoid specifically starting PA and rely on autospawn/socket activation

This --start is patched out in several downstreams to allow users to easily
disable PA by simply disabling autospawn.

If autospawn is enabled, then the first pactl command will start it and if not
it will fail and the script will exit.

When switching to systemd socket activation, we very much do not want to
start PA manually here. We could replace it with a
  systemctl --user start pulseaudio
but really it just makes sense to rely on the socket activation as this
should apply equally to non-systemd setups which use PA's own autospawn.
launch: Add systemd units for launching pulseaudio user instances

Change-Id: Ic422d604f8b01f33ea9d90c7c361c2bccf251609
launch: Disable autospawn by default when systemd daemon support is enabled.

This method is prefered over pulseaudio's built in systems so we should
try our best to ensure that it cannot be spawned outside of the mechanisms
desired.

We also disable the manual override of enabling the socket and force it to
be enabled at install time.

Change-Id: I18f5fc0f047bcda8c028c2bf44455bcc8958fa17
build-sys: Minor cosmetic tidyup of configure summary
move systemd include out from LIBWRAP

Change-Id: Iaac76ff870a4162741e11e0e1cb612b3ea4d022b
fix shadowed declaration warning in systemd patches

Change-Id: I92af0b162acf3b7e3430f61e4d7b889cd6d30443
change tizen ivi sockets to pulseaudio.socket

Change-Id: I148d3d30916c9b0c2eef0a3acedbf428fb667be6
add systemd socket activation files to spec

Change-Id: I1aa8c30d1fd3bbb4872718df65a3943de007a1d0