cmd/cue: swap BuildFile for BuildExpr in --path
A further simplification where we don't need to convert
an inline CUE expression into a file to build it.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: If02c40a27e8130605ce3b6e31642d236f46348be
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1233927
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Matthew Sackman <matthew@cue.works>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>