style: Normalize variable expansions in libs.deprecated/*

These files stay deprecated and out of the sourcing path for now, but
apply the same ${var} notation cleanup as the rest of the repo where
it's a pure notation fix. basedir.bash is left untouched: its bug is
a broken escape, not a notation issue, and it mirrors the one already
removed from _helpers.bash.

libs.deprecated/grepp.bash

@@ -1 +1 @@
-grepp() { x=$1; shift; perl -00ne ' print if /'"$x"'/i ' "$*" ; }
+grepp() { x=$1; shift; perl -00ne ' print if /'"${x}"'/i ' "$*" ; }