Add makefile for slapo-cloak

contrib/slapd-modules/cloak/Makefile

+# $OpenLDAP$
+CPPFLAGS+=-I../../../include -I../../../servers/slapd 
+CPPFLAGS+=-DSLAPD_OVER_CLOAK=SLAPD_MOD_DYNAMIC
+LIBS=-lldap_r -llber -lcrypto
+
+all: cloak.la
+
+cloak.lo:    cloak.c
+	$(LIBTOOL) --mode=compile $(CC) $(CPPFLAGS) -c $?
+
+cloak.la:    cloak.lo
+	$(LIBTOOL) --mode=link $(CC) -version-info 0:0:0 \
+		   -rpath $(PREFIX)/lib -module -o $@ $? $(LIBS)
+
+clean:
+	rm cloak.lo cloak.la