Pack all tarballs using pigz

This should speed up packing and rsync'ing of the sysroot and
base tarballs.
Signed-off-by: Simon McVittie <smcv@collabora.com>

flatdeb/debos-base.yaml

@@ -151,6 +151,20 @@ actions:
     compression: gz
     file: {{ $ospack }}
 
+  - action: run
+    label: pack base tarball
+    chroot: false
+    command: >
+      set -e;
+      echo;
+      tar -cf "$ARTIFACTDIR/{{ $ospack }}"
+      --numeric-owner
+      --sort=name
+      --use-compress-program="pigz -n --rsyncable"
+      -C "$ROOTDIR"
+      --transform="s,^./,,"
+      .
+
   - action: run
     label: manifests
     chroot: false

flatdeb/debos-runtimes.yaml

@@ -226,9 +226,10 @@ actions:
     command: >
       set -e;
       echo;
-      tar -zcf "$ARTIFACTDIR/{{ $sysroot_tarball }}"
+      tar -cf "$ARTIFACTDIR/{{ $sysroot_tarball }}"
       --numeric-owner
       --sort=name
+      --use-compress-program="pigz -n --rsyncable"
       -C "$ROOTDIR"
       --exclude="./script"
       --exclude="./src"