[gnome-panel] use AM_DISTCHECK_CONFIGURE_FLAGS

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 860c004406738a8ae0032475c0d124a13d974346
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Feb 15 23:00:19 2016 +0200

    use AM_DISTCHECK_CONFIGURE_FLAGS

 Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 5d4b488..28b0066 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -11,7 +11,7 @@ SUBDIRS = \
        po \
        $(NULL)
 
-DISTCHECK_CONFIGURE_FLAGS = \
+AM_DISTCHECK_CONFIGURE_FLAGS = \
        --enable-gtk-doc \
        --enable-introspection \
        $(NULL)