Add -E flag to sudo (fixes #8494)

Docker-DCO-1.1-Signed-off-by: Jérôme Petazzoni <jerome@docker.com> (github: jpetazzo)

hack/install.sh

@@ -42,7 +42,7 @@ user="$(id -un 2>/dev/null || true)"
 sh_c='sh -c'
 if [ "$user" != 'root' ]; then
 	if command_exists sudo; then
-		sh_c='sudo sh -c'
+		sh_c='sudo -E sh -c'
 	elif command_exists su; then
 		sh_c='su -c'
 	else