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')
href='/guix/refs/?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2'>refs</a><a class='active' href='/guix/log/gnu/packages/gimp.scm?showmsg=1'>log</a><a href='/guix/tree/gnu/packages/gimp.scm?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2'>tree</a><a href='/guix/commit/gnu/packages/gimp.scm?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2'>commit</a><a href='/guix/diff/gnu/packages/gimp.scm?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/gimp.scm'>
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<div class='path'>path: <a href='/guix/log/?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/gimp.scm?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2&amp;showmsg=1'>gimp.scm</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/gimp.scm?id=f95bf8436ae4bd5eb45077d8d8f04126184aefc2'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2023-01-03 12:07:46 -0500'>2023-01-03</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=4c123214669a9c54173cd89e0f86b603b23d93ea'>gnu: Remove Glimpse.</a></td><td>Leo Famulari</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
This package no longer builds and is abandoned upstream:

https://glimpse-editor.org/posts/a-project-on-hiatus/

* gnu/packages/gimp.scm (gegl-for-glimpse, glimpse): Remove variables.


</td></tr>
<tr class='logheader'><td><span title='2022-08-30 17:59:18 +0200'>2022-08-30</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=77c07d9a6149f41870684df587e1fee5dad78acd'>gnu: babl: Update to 0.1.96.</a></td><td>Marius Bakke</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (babl): Update to 0.1.96.


</td></tr>
<tr class='logheader'><td><span title='2022-06-18 13:07:10 -0300'>2022-06-18</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=ea6738c74fcf9a847a21b1b22b0dc571bea6df38'>gnu: gimp: Update to 2.10.32.</a></td><td>Vinicius Monego</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (gimp): Update to 2.10.32.


</td></tr>
<tr class='logheader'><td><span title='2022-06-18 13:07:10 -0300'>2022-06-18</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=0d7d5a05c741e545748c3b3cbe43bfece3e5697e'>gnu: gegl: Update to 0.4.36.</a></td><td>Vinicius Monego</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (gegl): Update to 0.4.36.


</td></tr>
<tr class='logheader'><td><span title='2022-06-18 13:07:10 -0300'>2022-06-18</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=f7882f7b756d432512b522cfa6ec302fc74ed9be'>gnu: babl: Update to 0.1.92.</a></td><td>Vinicius Monego</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (babl): Update to 0.1.92.


</td></tr>
<tr class='logheader'><td><span title='2022-05-31 14:53:44 -0400'>2022-05-31</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=5f2c56e739d03ba418dadb7f4dcb0bfb5f7ffd38'>gnu: glimpse: Drop Python 2 support.</a></td><td>Maxim Cournoyer</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (glimpse)[source]: Fix indentation.
[arguments]: Use gexps.
[phases]{install-sitecustomize}: Delete phase.
[native-inputs]: Use new style.
[inputs]: Use new style.  Delete python-2 and python2-pygtk.


</td></tr>
<tr class='logheader'><td><span title='2022-05-31 14:53:44 -0400'>2022-05-31</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/gimp.scm?id=8d71e5b2a5b5f5e6ca49e10a65384c298437b401'>gnu: gimp: Drop Python 2 support.</a></td><td>Maxim Cournoyer</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/gimp.scm (gimp)[inputs]: Delete python-2 and python2-pygtk.
[configure-flags]: Use gexps.  Add "--disable-python".
[phases]: Delete argument.
[inputs, native-inputs]: Use new style.


</td></tr>