[gnome-control-center] common: Fix parallel build

[Bastien Nocera <hadess src gnome org>]

commit 3ab88c7ff0dc8774fe6cbcac5e8fc23bed80095d
Author: Bastien Nocera <hadess hadess net>
Date:   Sun Jul 19 19:33:43 2015 +0200

    common: Fix parallel build
    
    https://bugzilla.gnome.org/show_bug.cgi?id=752596

 panels/common/Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/panels/common/Makefile.am b/panels/common/Makefile.am
index 3f691c6..7d0eaad 100644
--- a/panels/common/Makefile.am
+++ b/panels/common/Makefile.am
@@ -29,6 +29,8 @@ liblanguage_la_LIBADD =               \
 #libdevice
 GSD_COMMON_ENUM_FILES = gsd-common-enums.c gsd-common-enums.h
 
+BUILT_SOURCES += $(GSD_COMMON_ENUM_FILES)
+
 gsd-common-enums.h: gsd-device-manager.h Makefile
        $(AM_V_GEN)($(GLIB_MKENUMS) \
                        --fhead "#ifndef GSD_COMMON_ENUMS_H\n#define GSD_COMMON_ENUMS_H\n\n#include 
<glib-object.h>\n\nG_BEGIN_DECLS\n" \