bogofilter: create /usr/sbin before installing postfix-bogofilter there

Signed-off-by: W. Michael Petullo <mike@flyn.org>

mail/bogofilter/Makefile

@@ -39,7 +39,8 @@ CONFIGURE_ARGS += --disable-unicode
 
 define Package/bogofilter/install
 	$(INSTALL_DIR)  $(1)/etc/ \
-                        $(1)/usr/bin
+                        $(1)/usr/bin \
+                        $(1)/usr/sbin
 	$(INSTALL_CONF) $(PKG_BUILD_DIR)/bogofilter.cf.example $(1)/etc/bogofilter.cf
 	$(INSTALL_BIN) ./files/postfix-bogofilter $(1)/usr/sbin/postfix-bogofilter
 	$(CP) $(PKG_INSTALL_DIR)/usr/bin/bf_compact $(1)/usr/bin/