support unpacking of .tar.xz archives, no prereq on xzcat for now

SVN-Revision: 22517

include/unpack.mk

@@ -32,7 +32,11 @@ ifeq ($(strip $(UNPACK_CMD)),)
       EXT:=$(call ext,$(PKG_SOURCE:.$(EXT)=))
       DECOMPRESS_CMD:=bzcat $(DL_DIR)/$(PKG_SOURCE) |
     endif
-    ifeq ($(filter tgz tbz tbz2,$(EXT1)),$(EXT1))
+    ifeq ($(filter xz txz,$(EXT)),$(EXT))
+      EXT:=$(call ext,$(PKG_SOURCE:.$(EXT)=))
+      DECOMPRESS_CMD:=xzcat $(DL_DIR)/$(PKG_SOURCE) |
+    endif
+    ifeq ($(filter tgz tbz tbz2 txz,$(EXT1)),$(EXT1))
       EXT:=tar
     endif
     DECOMPRESS_CMD ?= cat $(DL_DIR)/$(PKG_SOURCE) |