Change Linux sysroot creator scripts to use XZ compression.

build/linux/sysroot_scripts/build_and_upload.py

Index: build/linux/sysroot_scripts/build_and_upload.py
diff --git a/build/linux/sysroot_scripts/build_and_upload.py b/build/linux/sysroot_scripts/build_and_upload.py
index bdbd73dddf5d0e0e0c884cfb7e1655300bcc71ed..78eaa6319e45072c4913c1f90ff7bac27f96f869 100755
--- a/build/linux/sysroot_scripts/build_and_upload.py
+++ b/build/linux/sysroot_scripts/build_and_upload.py
@@ -44,10 +44,10 @@ def build_and_upload(script_path, distro, release, arch, lock):
   run_script([script_path, 'BuildSysroot%s' % arch])
   run_script([script_path, 'UploadSysroot%s' % arch, revision])
 
-  tarball = '%s_%s_%s_sysroot.tgz' % (distro, release, arch.lower())
-  tgz_path = os.path.join(script_dir, "..", "..", "..", "out", "sysroot-build",
-                          release, tarball)
-  sha1sum = sha1sumfile(tgz_path)
+  tarball = '%s_%s_%s_sysroot.tar.xz' % (distro, release, arch.lower())
+  tarxz_path = os.path.join(script_dir, "..", "..", "..", "out",
+                            "sysroot-build", release, tarball)
+  sha1sum = sha1sumfile(tarxz_path)
   sysroot_dir = '%s_%s_%s-sysroot' % (distro, release, arch.lower())
 
   sysroot_metadata = {