Update systemd support from several GSD commits

Msg: Backout change from using free() to g_free() in systemd patch
Commit: f1f7bddf007c950608f5f8c5a771a7fb2ab187d5
From: Chris Kühl <[email protected]>

Msg: Require systemd 38 or greater when using --enable-systemd
Commit: ff551c6974cfa0801a368ee5c2406ce941ac8cab
From: Chris Kühl <[email protected]>

Msg: build: Disallow building with systemd v43 due to C++ incompatibility
Commit: 8a17cd6ff6b0ab4979c6ed8426724ce355d23679
From: Chris Kühl <[email protected]>

Msg: Check for logind, not for systemd
Commit: 4cf87daa48a8ab606afe5e3c2ac54c8f6276ba98
From: Martin Pitt <[email protected]>

4 files changed, 17 insertions, 13 deletions

diff --git a/configure.ac b/configure.ac
index 0edfd3b..411a977 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,6 +34,9 @@ GIOMM_REQUIRED=2.26.0
 GLIBMM_REQUIRED=2.22
 LIBXML_REQUIRED=2.0
 RSVG_REQUIRED=2.35
+SYSTEMD_REQUIRED=38
+# systemd v43 used the C++ keyword 'class' as a function parameter. This breaks the build for C++ programs.
+SYSTEMD_EXCLUDED=43
 
 AC_MSG_CHECKING([which gtk+ version to compile against])
 AC_ARG_WITH([gtk],
@@ -65,11 +68,14 @@ PKG_CHECK_MODULES(GMODULE,gmodule-2.0,[GMODULE_ADD="gmodule-2.0"],[GMODULE_ADD="
 PKG_CHECK_MODULES(PROCMAN,$GMODULE_ADD glib-2.0 >= $GLIB_REQUIRED libgtop-2.0 >= $LIBGTOP_REQUIRED libwnck-$LIBWNCK_API_VERSION >= $LIBWNCK_REQUIRED gtk+-$GTK_API_VERSION >= $GTK_REQUIRED mate-icon-theme >= $MATE_ICON_THEME_REQUIRED gtkmm-$GTKMM_API_VERSION >= $GTKMM_REQUIRED libxml-2.0 >= $LIBXML_REQUIRED librsvg-2.0 >= $RSVG_REQUIRED glibmm-2.4 >= $GLIBMM_REQUIRED giomm-2.4 >= $GIOMM_REQUIRED)
 
 have_systemd=no
-AC_ARG_ENABLE(systemd, AS_HELP_STRING([--disable-systemd], [disable systemd support]))
-if test "x$enable_systemd" != "xno"; then
-        PKG_CHECK_MODULES(SYSTEMD, [ libsystemd-daemon libsystemd-login ],
-                [AC_DEFINE(HAVE_SYSTEMD, 1, [Define if systemd is available]) have_systemd=yes], have_systemd=no)
-        if test "x$have_systemd" = xno -a "x$enable_systemd" = xyes; then
+AC_ARG_ENABLE(systemd, AS_HELP_STRING([--disable-systemd], [disable systemd support]),,enable_systemd=no)
+	if test "x$enable_systemd" != "xno"; then
+		PKG_CHECK_MODULES(SYSTEMD, [ libsystemd-login >= $SYSTEMD_REQUIRED ],
+					   [ PKG_CHECK_MODULES(SYSTEMD_EX, [ libsystemd-login = $SYSTEMD_EXCLUDED ],
+									   AC_MSG_ERROR([*** systemd v43 found but it has a bug in its header files (uses C++ keyword)]), # Can't use systemd v43
+									   [AC_DEFINE(HAVE_SYSTEMD, 1, [Define if systemd is available]) have_systemd=yes])],
+					   have_systemd=no)
+if test "x$have_systemd" = xno; then
                 AC_MSG_ERROR([*** systemd support requested but libraries not found])
         fi
 fi
diff --git a/src/procdialogs.cpp b/src/procdialogs.cpp
index 7d7aace..95b2527 100644
--- a/src/procdialogs.cpp
+++ b/src/procdialogs.cpp
@@ -25,10 +25,6 @@
 #include <signal.h>
 #include <string.h>
 
-#ifdef HAVE_SYSTEMD
-#include <systemd/sd-daemon.h>
-#endif
-
 #include "procdialogs.h"
 #include "proctable.h"
 #include "callbacks.h"
@@ -479,7 +475,7 @@ create_field_page(GtkWidget *tree, const char* text)
              column_id == COL_SEAT ||
              column_id == COL_OWNER)
 #ifdef HAVE_SYSTEMD
-            && sd_booted() <= 0
+            && !LOGIND_RUNNING()
 #endif
                 )
             continue;
diff --git a/src/proctable.cpp b/src/proctable.cpp
index 25b1f36..20f0db5 100644
--- a/src/proctable.cpp
+++ b/src/proctable.cpp
@@ -45,7 +45,6 @@
 #include <list>
 
 #ifdef HAVE_SYSTEMD
-#include <systemd/sd-daemon.h>
 #include <systemd/sd-login.h>
 #endif
 
@@ -488,7 +487,7 @@ proctable_new (ProcData * const procdata)
     }
 
 #ifdef HAVE_SYSTEMD
-    if (sd_booted() <= 0)
+    if (!LOGIND_RUNNING())
 #endif
     {
         GtkTreeViewColumn *column;
@@ -756,7 +755,7 @@ get_process_systemd_info(ProcInfo *info)
 #ifdef HAVE_SYSTEMD
     uid_t uid;
 
-    if (sd_booted() <= 0)
+    if (!LOGIND_RUNNING())
         return;
 
     free(info->unit);
diff --git a/src/util.h b/src/util.h
index 22a9a14..26aed19 100644
--- a/src/util.h
+++ b/src/util.h
@@ -28,6 +28,9 @@ inline int procman_cmp(T x, T y)
 #define PROCMAN_CMP(X, Y) procman_cmp((X), (Y))
 #define PROCMAN_RCMP(X, Y) procman_cmp((Y), (X));
 
+/* check if logind is running */
+#define LOGIND_RUNNING() (access("/run/systemd/seats/", F_OK) >= 0)
+
 GtkWidget*
 procman_make_label_for_mmaps_or_ofiles(const char *format,
                                        const char *process_name,