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')
4e19b4'>refs</a><a class='active' href='/guix/log/build-aux/xgettext.scm'>log</a><a href='/guix/tree/build-aux/xgettext.scm?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>tree</a><a href='/guix/commit/build-aux/xgettext.scm?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>commit</a><a href='/guix/diff/build-aux/xgettext.scm?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/build-aux/xgettext.scm'>
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<div class='path'>path: <a href='/guix/log/?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>root</a>/<a href='/guix/log/build-aux?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>build-aux</a>/<a href='/guix/log/build-aux/xgettext.scm?id=297e88edff2b532a0ebf6bab846677c08e4e19b4'>xgettext.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/build-aux/xgettext.scm?id=297e88edff2b532a0ebf6bab846677c08e4e19b4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-04-19 16:45:41 +0200'>2024-04-19</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=f83b5274c8d67a9bccf8881cc4f87d76a3d172de'>maint: Support `make doc-pot-update' from a tarball.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: Move setting of environment variables to shell
header.
(main): Use SOURCE_DATE_EPOCH as fallback for timestamp.  This fixes running
from a tarball.
* Makefile.am (EXTRA_DIST): Add it.

Change-Id: Ic487587b22495868fd2a21545a13dc9e3458299c
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>
<tr><td><span title='2024-04-14 11:41:41 +0200'>2024-04-14</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=e5dda412c2e28fb65a549824f492895e72c33813'>maint: Fix header.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: Add `Guix' parts to header.

Change-Id: I4fb03b8b0588f0482bcb1a095518b6751d111031
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>
<tr><td><span title='2024-04-14 10:29:11 +0200'>2024-04-14</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=6c63c366776643e5831c50a2b7e29bad93273327'>maint: Use xgettext.scm wrapper to create .PO files reproducibly.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: New script.
* po/guix/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.
* po/packages/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.

Change-Id: I71b6b843970090f765f46ac346b92a346560e3f0
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>