[gnome-control-center] shell: Fix distcheck

[Bastien Nocera <hadess src gnome org>]

commit d6df12fa253487cf1d74981f80dcdb17ebf1c452
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Jan 15 16:16:03 2013 +0100

    shell: Fix distcheck
    
    No overriding EXTRA_DIST please.

 shell/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/shell/Makefile.am b/shell/Makefile.am
index 2fef094..95a7362 100644
--- a/shell/Makefile.am
+++ b/shell/Makefile.am
@@ -129,7 +129,7 @@ test_hostname_SOURCES = hostname-helper.c hostname-helper.h test-hostname.c
 test_hostname_LDADD = $(PANEL_LIBS) $(INFO_PANEL_LIBS)
 test_hostname_CFLAGS = $(INCLUDES)
 
-EXTRA_DIST = hostnames-test.txt
+EXTRA_DIST += hostnames-test.txt
 check-local: test-hostname
 	$(builddir)/test-hostname $(srcdir)/hostnames-test.txt > /dev/null