Use gzip instead of xz for original source archives

xz adds many minutes to build time

Change-Id: I85c09ef8a86249009c3b7862d7136f8934f30ebf
diff --git a/packages.mk b/packages.mk
index 23db16f..fab9f23 100644
--- a/packages.mk
+++ b/packages.mk
@@ -57,11 +57,11 @@
 	mkdir -p $(PRODUCT_OUT)/obj/$1
 	rsync -rl --exclude .git/ $(ROOTDIR)/$2/* $(PRODUCT_OUT)/obj/$1
 	cp -r $(ROOTDIR)/packages/$1/debian $(PRODUCT_OUT)/obj/$1
-	tar -C $(PRODUCT_OUT)/obj --exclude=debian/ -cJf \
-		$(PRODUCT_OUT)/obj/$1_$$(call get-deb-version-orig,$1).orig.tar.xz \
+	tar -C $(PRODUCT_OUT)/obj --exclude=debian/ -czf \
+		$(PRODUCT_OUT)/obj/$1_$$(call get-deb-version-orig,$1).orig.tar.gz \
 		$1
-	tar -C $(PRODUCT_OUT)/obj/$1 -cJf \
-		$(PRODUCT_OUT)/obj/$1_$$(call get-deb-version-full,$1).debian.tar.xz \
+	tar -C $(PRODUCT_OUT)/obj/$1 -czf \
+		$(PRODUCT_OUT)/obj/$1_$$(call get-deb-version-full,$1).debian.tar.gz \
 		debian
 
 	cd $(PRODUCT_OUT)/obj/$1; pdebuild \