Be explicit about setting SUBDIRS_DIST

Make sure we don't end up having libjemalloc twice in SUBDIRS_DIST as
this will cause failures when doing make distclean.


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3220 d4fa192b-c00b-0410-8231-f00ffab90ce4

lib/Makefile.am

@@ -7,5 +7,9 @@ SUBDIRS = \
 	libvcl \
 	@JEMALLOC_SUBDIR@
 
-DIST_SUBDIRS = 	$(SUBDIRS) \
+DIST_SUBDIRS = 	\
+	libvarnish \
+	libvarnishapi \
+	libvarnishcompat \
+	libvcl \
 	libjemalloc