build.sh: multithread compression

Use xz's multithreaded compression for a significant speedup in build
time.

diff --git a/image/build.sh b/image/build.sh
index 66234c1..db9c2ee 100755 (executable)
--- a/image/build.sh
+++ b/image/build.sh
@@ -17,7 +17,9 @@ poudriere image \
        -s 3g -t usb
 
 # Put the domotica image in the installer overlay
-xz -v -z -c /usr/local/poudriere/data/images/domotica.img > overlay/installer/domotica.img.xz
+xz -v -z -c \
+       -T 0 \
+       /usr/local/poudriere/data/images/domotica.img > overlay/installer/domotica.img.xz
 
 poudriere image \
        -j $JAIL -p $PORTS -f $PACKAGES \