Get wayland-session wrapper from environment.

diff --git a/daemon/gdm-session.c b/daemon/gdm-session.c
index 3b83fcd3..e60e6a57 100644
--- a/daemon/gdm-session.c
+++ b/daemon/gdm-session.c
@@ -2933,8 +2933,9 @@ gdm_session_start_session (GdmSession *self,
                                                            allow_remote_connections? "--allow-remote-connections " : "",
                                                            command);
                         } else {
-                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"%s\"",
+                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"%s %s\"",
                                                            register_session ? "--register-session " : "",
+                                                           g_getenv ("GDM_WAYLAND_SESSION"),
                                                            command);
                         }
                 } else if (run_xsession_script) {
@@ -2965,8 +2966,9 @@ gdm_session_start_session (GdmSession *self,
                                                            register_session ? "--register-session " : "",
                                                            self->selected_program);
                         } else {
-                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"dbus-run-session -- %s\"",
+                                program = g_strdup_printf (LIBEXECDIR "/gdm-wayland-session %s\"dbus-run-session -- %s %s\"",
                                                            register_session ? "--register-session " : "",
+                                                           g_getenv ("GDM_WAYLAND_SESSION"),
                                                            self->selected_program);
                         }
                 } else {
='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=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>root</a>/<a href='/guix/log/gnu?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>gnu</a>/<a href='/guix/log/gnu/packages?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>packages</a>/<a href='/guix/log/gnu/packages/aux-files?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>aux-files</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>linux-libre</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre/4.14-i686.conf?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce'>4.14-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/4.14-i686.conf?id=d78ca1cbb17e35fa935a9030bf8e214407b6b4ce&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-07-15 01:54:26 -0400'>2021-07-15</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/4.14-i686.conf?id=12763e4d3a90d113da85f5c9d116889982021a8f'>gnu: linux-libre: Default to the 'schedutil' CPU scaling governor.</a><span class='msg-avail'>...<span class='msg-tooltip'>For more information about these configuration options, read
&lt;https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt&gt; or the
document 'Documentation/admin-guide/pm/cpufreq.rst' in the linux-libre
source distribution.

* 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/4.9-i686.conf,
gnu/packages/aux-files/linux-libre/4.9-x86_64.conf,
gnu/packages/aux-files/linux-libre/5.10-i686.conf,
gnu/packages/aux-files/linux-libre/5.10-x86_64.conf,
gnu/packages/aux-files/linux-libre/5.12-i686.conf,
gnu/packages/aux-files/linux-libre/5.12-x86_64.conf,
gnu/packages/aux-files/linux-libre/5.13-i686.conf,
gnu/packages/aux-files/linux-libre/5.13-x86_64.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: Unset
'CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE' and set
'CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL=y'.
</span></span></td><td>Leo Famulari</td></tr>