Set amongst the remote woodlands of Basque Country, Spain, this Spanish-UK collaboration feels like a psychological thriller-adventure drawing inspiration from films such as “Deliverance,” with touches of “The Shuttered Room” and thematic echoes of “Straw Dogs.” The original title, “Forest of Shadows,” is more evocative than the English release's rather bland moniker, “The Backwoods.” Maintaining a sense of realis…