[metacity] build: fix distcheck

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 405436d1ac6545c4dc7878a46824c0ee1c4b1ad3
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Fri Feb 12 10:48:30 2016 +0200

    build: fix distcheck

 src/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index 3a6d612..67b6a9e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -119,7 +119,7 @@ bin_PROGRAMS=metacity
 metacity_LDADD= METACITY_LIBS@ $(top_builddir)/libmetacity/libmetacity.la
 
 testboxes_SOURCES=include/util.h core/util.c include/boxes.h core/boxes.c core/testboxes.c
-testgradient_SOURCES=../libmetacity/meta-gradient.h ../libmetacity/meta-gradient.c ui/testgradient.c
+testgradient_SOURCES=../libmetacity/meta-gradient-private.h ../libmetacity/meta-gradient.c ui/testgradient.c
 testasyncgetprop_SOURCES=core/async-getprop.h core/async-getprop.c core/testasyncgetprop.c
 
 noinst_PROGRAMS=testboxes testgradient testasyncgetprop