Fix build with boost 1.69

This is also fixed with master with boost bump which we do not need
here.

Change-Id: I61caec10c0c6d442cef3d51c31eaff01f18b89e3
Reviewed-on: https://gerrit.libreoffice.org/69310Reviewed-by: Tomáš Chvátal <tchvatal@suse.cz>
Tested-by: Tomáš Chvátal <tchvatal@suse.cz>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sfx2/source/appl/shutdownicon.cxx

@@ -143,7 +143,7 @@ bool LoadModule()
 #endif // ENABLE_QUICKSTART_APPLET
     }
     assert(!boost::logic::indeterminate(loaded));
-    return loaded;
+    return bool(loaded);
 }
 
 }