Don't install systemd units unless using libsystemd session tracking.

Submitted upstream:

  https://gitlab.freedesktop.org/polkit/polkit/-/merge_requests/134

diff --git a/data/meson.build b/data/meson.build
--- a/data/meson.build
+++ b/data/meson.build
@@ -26,7 +26,7 @@ if enable_pam
   )
 endif
 
-if enable_logind
+if session_tracking == 'libsystemd-login'
   configure_file(
     input: 'polkit.service.in',
     output: '@BASENAME@',
diff --git a/meson.build b/meson.build
--- a/meson.build
+++ b/meson.build
@@ -199,7 +199,7 @@ if enable_logind
 
   # systemd unit / service files
   systemd_systemdsystemunitdir = get_option('systemdsystemunitdir')
-  if systemd_systemdsystemunitdir == ''
+  if systemd_systemdsystemunitdir == '' and session_tracking == 'libsystemd-login'
     systemd_dep = dependency('systemd', not_found_message: 'systemd required but not found, please provide a valid systemd user unit dir or disable it')
     # FIXME: systemd.pc file does not use variables with relative paths, so `define_variable` cannot be used
     systemd_systemdsystemunitdir = systemd_dep.get_pkgconfig_variable('systemdsystemunitdir')
f='/guix/refs/?id=b611597af8641b388dc9f8935b85895a71e9fb52'>refs</a><a class='active' href='/guix/log/gnu/packages/aux-files/linux-libre/5.4-i686.conf'>log</a><a href='/guix/tree/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=b611597af8641b388dc9f8935b85895a71e9fb52'>tree</a><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=b611597af8641b388dc9f8935b85895a71e9fb52'>commit</a><a href='/guix/diff/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=b611597af8641b388dc9f8935b85895a71e9fb52'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/aux-files/linux-libre/5.4-i686.conf'>
<input type='hidden' name='id' value='b611597af8641b388dc9f8935b85895a71e9fb52'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=b611597af8641b388dc9f8935b85895a71e9fb52'>root</a>/<a href='/guix/log/gnu?id=b611597af8641b388dc9f8935b85895a71e9fb52'>gnu</a>/<a href='/guix/log/gnu/packages?id=b611597af8641b388dc9f8935b85895a71e9fb52'>packages</a>/<a href='/guix/log/gnu/packages/aux-files?id=b611597af8641b388dc9f8935b85895a71e9fb52'>aux-files</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre?id=b611597af8641b388dc9f8935b85895a71e9fb52'>linux-libre</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=b611597af8641b388dc9f8935b85895a71e9fb52'>5.4-i686.conf</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=b611597af8641b388dc9f8935b85895a71e9fb52&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-01-15 14:31:21 +0100'>2020-01-15</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=2c97c980a0ca5f77464cd74207e29d835376f85b'>gnu: linux-libre: Include more framebuffer font sizes.</a><span class='msg-avail'>...<span class='msg-tooltip'>Add the 32x16 Terminus font for ‘high-DPI’ screens, and a 6x10 font that
allows for more (debugging) information to be displayed on standard-DPI
ones, while still being pleasant to read.

* gnu/packages/aux-files/linux-libre/4.14-arm.conf,
gnu/packages/aux-files/linux-libre/4.14-i686.conf,
gnu/packages/aux-files/linux-libre/4.14-x86_64.conf,
gnu/packages/aux-files/linux-libre/4.19-arm.conf,
gnu/packages/aux-files/linux-libre/4.19-arm64.conf,
gnu/packages/aux-files/linux-libre/4.19-i686.conf,
gnu/packages/aux-files/linux-libre/4.19-x86_64.conf,
gnu/packages/aux-files/linux-libre/4.4-i686.conf,
gnu/packages/aux-files/linux-libre/4.4-x86_64.conf,
gnu/packages/aux-files/linux-libre/4.9-i686.conf,
gnu/packages/aux-files/linux-libre/4.9-x86_64.conf,
gnu/packages/aux-files/linux-libre/5.4-arm-veyron.conf,
gnu/packages/aux-files/linux-libre/5.4-arm.conf,
gnu/packages/aux-files/linux-libre/5.4-arm64.conf,
gnu/packages/aux-files/linux-libre/5.4-i686.conf,
gnu/packages/aux-files/linux-libre/5.4-x86_64.conf:
Set CONFIG_FONTS=y, CONFIG_FONT_TER16x32=y, and CONFIG_FONT_6x10=y.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-12-18 23:07:44 -0500'>2019-12-18</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.4-i686.conf?id=952820c53964a3ee6fdca94e15771eb1097c87be'>gnu: linux-libre: Update to 5.4.5.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/aux-files/linux-libre/5.3-arm-veyron.conf,
gnu/packages/aux-files/linux-libre/5.3-arm.conf,
gnu/packages/aux-files/linux-libre/5.3-arm64.conf,
gnu/packages/aux-files/linux-libre/5.3-i686.conf,
gnu/packages/aux-files/linux-libre/5.3-x86_64.conf: Delete files.
* gnu/packages/aux-files/linux-libre/5.4-arm-veyron.conf,
gnu/packages/aux-files/linux-libre/5.4-arm.conf,
gnu/packages/aux-files/linux-libre/5.4-arm64.conf,
gnu/packages/aux-files/linux-libre/5.4-i686.conf,
gnu/packages/aux-files/linux-libre/5.4-x86_64.conf: New files.
* Makefile.am (AUX_FILES): Update accordingly.
* gnu/packages/patches/linux-libre-active-entropy.patch: Delete file.
* gnu/local.mk (dist_patch_DATA): Remove it.
* gnu/packages/linux.scm (deblob-scripts-5.3, linux-libre-5.3-version)
(linux-libre-5.3-pristine-source, linux-libre-5.3-source)
(linux-libre-headers-5.3, linux-libre-5.3): Remove variables.
(deblob-scripts-5.4, linux-libre-5.4-version)
(linux-libre-5.4-pristine-source, linux-libre-5.4-source)
(linux-libre-headers-5.4, linux-libre-5.4): New variables.
(linux-libre-version, linux-libre-pristine-source)
(linux-libre-source, linux-libre): Point to linux-libre-5.4*.
</span></span></td><td>Mark H Weaver</td></tr>