face: use /run/nfd.sock on Linux

refs #5039

Change-Id: I10902725912a8f194ce6da6590378c1029955f80
diff --git a/wscript b/wscript
index 7bf7069..a7e4906 100644
--- a/wscript
+++ b/wscript
@@ -202,7 +202,8 @@
         target='nfd.conf.sample',
         install_path='${SYSCONFDIR}/ndn',
         IF_HAVE_LIBPCAP='' if bld.env.HAVE_LIBPCAP else '; ',
-        IF_HAVE_WEBSOCKET='' if bld.env.HAVE_WEBSOCKET else '; ')
+        IF_HAVE_WEBSOCKET='' if bld.env.HAVE_WEBSOCKET else '; ',
+        UNIX_SOCKET_PATH='/run/nfd.sock' if Utils.unversioned_sys_platform() == 'linux' else '/var/run/nfd.sock')
 
     bld.install_files('${SYSCONFDIR}/ndn', 'autoconfig.conf.sample')