Fix build as non-root user (BUILD_AS_NON_ROOT=yes in poudriere.conf)
reported by pkg-fallout. While we're at it turn off annoying
CT_LOG_PROGRESS_BAR spinner (which also makes the build log huge).

Reviewed by: matthew (mentor)
Approved by: matthew (mentor)
Differential Revision: https://reviews.freebsd.org/D15312