docs: Ensure CLEANFILES is set before we use +=
authorColin Walters <walters@verbum.org>
Sat, 25 Aug 2012 21:13:43 +0000 (17:13 -0400)
committerColin Walters <walters@verbum.org>
Sat, 25 Aug 2012 21:13:43 +0000 (17:13 -0400)
commitac7c050d377f6815534074b855cdf74f02cf96b2
tree284779b08c9fd10a1b63732ca12df5d852ca00ae
parentdbad8304ff123f7fe242bdd8a8cfcb7eef8afce6
docs: Ensure CLEANFILES is set before we use +=

We need to be defensive about this in the case where gtk-doc.make is
empty.
docs/reference/gio/Makefile.am
docs/reference/glib/Makefile.am
docs/reference/gobject/Makefile.am