Go modules seem to have too restrictive permissions on
its builddir, making xbps-uchroot(1) unable to remove
its directory tree due to insufficient permissions.
Run nftw() twice, the first run to set chmod 755, and
second run to remove the file.
Fixes `xbps-src -t` with any pkg that uses `build_style=go`.
This should avoid lots of temp dirs in the buildbot
builders while building go modules and others.
f6a6385b42