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')
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<div class='path'>path: <a href='/guix/log/?id=d41a1c3c1efbbfcfb7c9720499084d6ffb933cae'>root</a>/<a href='/guix/log/tests?id=d41a1c3c1efbbfcfb7c9720499084d6ffb933cae'>tests</a>/<a href='/guix/log/tests/store-database.scm?id=d41a1c3c1efbbfcfb7c9720499084d6ffb933cae'>store-database.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/tests/store-database.scm?id=d41a1c3c1efbbfcfb7c9720499084d6ffb933cae&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-04-15 22:36:42 +0200'>2024-04-15</span></td><td><a href='/guix/commit/tests/store-database.scm?id=54be7795b5cc2f6cad05f8649121372c9d5af806'>utils: Don’t re-export ‘call-with-temporary-output-file’.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2024-04-03 17:30:53 +0100'>2024-04-03</span></td><td><a href='/guix/commit/tests/store-database.scm?id=c9cd16c630ccba655b93ff32fd9a99570b4f5373'>store: database: Rename a couple of procedures.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2021-01-31 21:49:58 +0100'>2021-01-31</span></td><td><a href='/guix/commit/tests/store-database.scm?id=13a7d2a538b00aa0a8cf9b999f1a4ff3e5959af9'>database: Validate #:nar-size and #:time when registering store items.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-12-15 17:32:11 +0100'>2020-12-15</span></td><td><a href='/guix/commit/tests/store-database.scm?id=3169c93903c20cea000335d59560eac7f28e8f92'>database: Remove 'register-path'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-12-15 17:32:11 +0100'>2020-12-15</span></td><td><a href='/guix/commit/tests/store-database.scm?id=0682cc593688e7d9a435ca69f05320aa87df06d0'>database: Remove #:deduplicate? and #:reset-timestamps? from 'register-path'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-21 12:39:14 +0100'>2020-11-21</span></td><td><a href='/guix/commit/tests/store-database.scm?id=ac435c14a627f620bf6719efbdd214a12b33716e'>store-database: Add test checking the directory mtime after 'register-path'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-07-20 15:01:33 +0200'>2018-07-20</span></td><td><a href='/guix/commit/tests/store-database.scm?id=e4752118691e41ae8307649d1abfd4739b3e4bfa'>database: Reset timestamps to one second after the Epoch.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-14 11:17:00 +0200'>2018-06-14</span></td><td><a href='/guix/commit/tests/store-database.scm?id=df2f6400b1fbc282ef4d6dd7124ea1c17adc23c2'>store: Remove 'register-path'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-14 11:17:00 +0200'>2018-06-14</span></td><td><a href='/guix/commit/tests/store-database.scm?id=ef1297e8c74a0358d2538a5dd43d50cde7bf14a3'>database: 'sqlite-register' takes a database, not a file name.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-14 11:16:58 +0200'>2018-06-14</span></td><td><a href='/guix/commit/tests/store-database.scm?id=f8f9f7cabca3f0ea1f8b8cb4fecfc45889bdfb94'>database: Fail registration when encountering unregistered references.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-14 11:16:58 +0200'>2018-06-14</span></td><td><a href='/guix/commit/tests/store-database.scm?id=3931c76154d4f418d5ea9acc5e47bf911d371c24'>database: 'with-database' can now initialize new databases.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-01 15:35:32 +0200'>2018-06-01</span></td><td><a href='/guix/commit/tests/store-database.scm?id=7f9d184d9b688d13ce76eefabaddcfa76bdde2b5'>Add (gnu store database).</a><span class='msg-avail'>...</span></td><td>Caleb Ristvedt</td></tr>