Enable bash -x if GETUTO_DEBUG is set

Support enabling verbose bash output if GETUTO_DEBUG is set. Due
getuto often being called via portage it is not trivial to get debug
output. Especially since setting

PORTAGE_TRUST_HELPER="bash -x /usr/bin/getuto"

fails with

!!! Portage trust helper bash -x /usr/bin/getuto for binary packages not found
!!! Continuing, but did you install app-portage/getuto?

getuto

@@ -18,6 +18,8 @@
 # sec-keys/openpgp-keys-gentoo-release
 # sys-apps/gentoo-functions
 
+[[ ${GETUTO_DEBUG} ]] && set -x
+
 QUIET='1'
 
 [[ $(whoami) == 'root' ]] || { echo "${0} must be run as root!" ; exit 100 ; }