[gnome-documents] build: fix a typo

[Cosimo Cecchi <cosimoc src gnome org>]

commit 15318ca8e5f3ee715379d8a3378388d43102654c
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Wed Feb 22 00:40:06 2012 +0100

    build: fix a typo

 src/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index f2a344a..da98791 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -78,5 +78,5 @@ service_DATA = $(service_in_files:.service.in=.service)
 	$(AM_V_GEN) [ -d $(@D) ] || $(mkdir_p) $(@D) ; \
 	            sed -e "s|\ libexecdir\@|$(libexecdir)|" $< > $  tmp && mv $  tmp $@
 
-CLEANFILES = += $(service_DATA)
+CLEANFILES += $(service_DATA)
 EXTRA_DIST += $(service_in_files)