fix remaining configuration warts

builds clealy as a test crate, without any dependency on
xous proper for configurations that don't involve xous.

.cargo/config

@@ -1,2 +0,0 @@
-#[build]
-#target="x86_64-unknown-linux-gnu"

Cargo.toml

@@ -52,21 +52,15 @@ packed_simd = { version = "0.3.4", package = "packed_simd_2", features = ["into_
 zeroize = { version = "1", default-features = false }
 fiat-crypto = { version = "0.1.6", optional = true}
 
-# 1. eliminate xous-engine-25519 crate
-# 2. engine-25519 refers to a "0.1.0"
-# 3. patch engine-25519 with a workspace patch in Xous
-# 4. make a betrusted-soc accelerated feature configuration
-# 5. make engine-25519 dependency only used when the betrusted-soc feature is specified
-# 6. test that cargo test still works in `std`
-
 # Betrusted/Precursor dependency set
-#[dependencies.engine-25519]
-#version = "0.1.0"
-#optional = true
+[dependencies.engine-25519]
+git="https://github.com/betrusted-io/xous-engine-25519.git"
+rev="63d3d1f30736022e791deaacf4dd62c00b42fe2e"
+optional = true
+
 [dependencies.engine25519-as]
 git="https://github.com/betrusted-io/engine25519-as.git"
 rev="6681e73c1fdc4a460b5ef9f9c7c91aef546d00f3"
-#path="../engine25519-as"
 default-features = false
 features = []
 optional = true
@@ -74,7 +68,6 @@ optional = true
 [dev-dependencies.engine25519-as]
 git="https://github.com/betrusted-io/engine25519-as.git"
 rev="6681e73c1fdc4a460b5ef9f9c7c91aef546d00f3"
-#path="../engine25519-as"
 
 [features]
 nightly = ["subtle/nightly"]
@@ -96,6 +89,6 @@ simd_backend = ["nightly", "u64_backend", "packed_simd"]
 # in some future release.
 avx2_backend = ["simd_backend"]
 # the betrusted backend uses the curve25519 hardware accelerator in betrusted-soc
-#betrusted = ["engine-25519", "engine25519-as"]
+betrusted = ["engine-25519", "engine25519-as"]
 
 [workspace]

src/field.rs

@@ -479,6 +479,8 @@ mod test {
 
     #[test]
     fn make_vectors() {
+        // reminder to self: to create just this vector, run
+        // cargo test field::test::make_vectors
         use std::fs::File;
         use std::io::prelude::*;
         use std::path::Path;