Change Linux sysroot creator scripts to use XZ compression.

build/linux/sysroot_scripts/sysroot-creator.sh

Index: build/linux/sysroot_scripts/sysroot-creator.sh
diff --git a/build/linux/sysroot_scripts/sysroot-creator.sh b/build/linux/sysroot_scripts/sysroot-creator.sh
index bc8bc7ab14ee5af7db6847d08850e0f7851670c2..59ddaa2fd204aeddf6a0a50c90b235b9b3be1696 100644
--- a/build/linux/sysroot_scripts/sysroot-creator.sh
+++ b/build/linux/sysroot_scripts/sysroot-creator.sh
@@ -155,7 +155,7 @@ SanityCheck() {
 
   # This is where the staging sysroot is.
   INSTALL_ROOT="${BUILD_DIR}/${DIST}_${ARCH_LOWER}_staging"
-  TARBALL="${BUILD_DIR}/${DISTRO}_${DIST}_${ARCH_LOWER}_sysroot.tgz"
+  TARBALL="${BUILD_DIR}/${DISTRO}_${DIST}_${ARCH_LOWER}_sysroot.tar.xz"
 
   if ! mkdir -p "${INSTALL_ROOT}" ; then
     echo "ERROR: ${INSTALL_ROOT} can't be created."
@@ -178,7 +178,7 @@ ClearInstallDir() {
 
 CreateTarBall() {
   Banner "Creating tarball ${TARBALL}"
-  tar zcf ${TARBALL} -C ${INSTALL_ROOT} .
+  tar Jcf ${TARBALL} -C ${INSTALL_ROOT} .
 }
 
 ExtractPackageGz() {