[mutter] doc: Fix make dist

[Rico Tzschichholz <ricotz src gnome org>]

commit 44a60eb7e999b7ab1fdcd5950824236dac49adde
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Mon Dec 29 19:38:49 2014 +0100

    doc: Fix make dist

 doc/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 12dc522..4440998 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1,4 +1,4 @@
 SUBDIRS = man reference
 
-EXTRA_DIST=theme-format.txt dialogs.txt code-overview.txt \
+EXTRA_DIST = dialogs.txt code-overview.txt \
        how-to-get-focus-right.txt rationales.txt