[sysprof] build: Add --enable-sysprofd configure flag

[Christian Hergert <chergert src gnome org>]

commit a7a6c59bdaff30d190aec4b4bb028c3e1112cb69
Author: Jussi Kukkonen <jussi kukkonen intel com>
Date:   Tue Jun 21 10:23:33 2016 +0300

    build: Add --enable-sysprofd configure flag
    
    This is useful to ensure reproducible builds.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=767902

 configure.ac |   21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index dc52d93..2246d5a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -113,12 +113,23 @@ PKG_CHECK_MODULES(SYSTEMD,
                   [have_systemd=yes],
                   [have_systemd=no])
 
-enable_sysprofd=no
-AS_IF([test "$have_polkit" = "yes" && test "$have_systemd" = "yes"],[
-       enable_sysprofd=yes
+# sysprofd requires libsystemd and polkit, and is required to run
+# the ui without root permissions
+AC_ARG_ENABLE([sysprofd],
+              [AS_HELP_STRING([--enable-sysprofd=@<:@yes/no/auto@:>@],
+                              [Build Sysprof D-Bus daemon.])],
+              [enable_sysprofd=$enableval],
+              [enable_sysprofd=auto])
+AS_IF([test "$enable_sysprofd" = "auto"],[
+        AS_IF([test "$have_polkit" = "yes" && test "$have_systemd" = "yes"],
+              [enable_sysprofd=yes],
+              [enable_sysprofd=no])
+])
+AS_IF([test "$enable_sysprofd" = "yes"],[
+        AS_IF([test "$have_systemd" = "yes" && test "$have_polkit" = "yes"],[],[
+                AC_MSG_ERROR([--enable-sysprofd requires libsystemd >= systemd_required_version and 
polkit-gobject-1])
+        ])
 ])
-
-# we require systemd for sysprofd
 AM_CONDITIONAL(ENABLE_SYSPROFD, [test "$enable_sysprofd" = "yes"])
 
 # we might be building sysprof-cli without the UI