build: reduce USB image size

There's no need for a lot of extra space. Enough to contain an extra
image, and that'll do it.

diff --git a/image/build.sh b/image/build.sh
index ba5faf6..9d507da 100755 (executable)
--- a/image/build.sh
+++ b/image/build.sh
@@ -13,4 +13,4 @@ poudriere image \
        -b \
        -c overlay/usb \
        -n pennestraat \
-       -s 20g -t usb
+       -s 4g -t usb