Hook SHA256 into the build

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3436 d4fa192b-c00b-0410-8231-f00ffab90ce4

lib/libvarnish/Makefile.am

@@ -24,6 +24,7 @@ libvarnish_la_SOURCES = \
 	vlu.c \
 	vpf.c \
 	vsb.c \
+	vsha256.c \
 	vss.c \
 	vtmpfile.c