tar: bump version

Fixes #69

package/tar/tar.mk

@@ -3,7 +3,7 @@
 # tar
 #
 #############################################################
-GNUTAR_VERSION:=1.18
+GNUTAR_VERSION:=1.21
 GNUTAR_SOURCE:=tar-$(GNUTAR_VERSION).tar.bz2
 GNUTAR_SITE:=$(BR2_GNU_MIRROR)/tar/
 GNUTAR_DIR:=$(BUILD_DIR)/tar-$(GNUTAR_VERSION)