chacha20: fix big endian failure and test in CI (#447)

Fixes failure introduced in #437, and updates CI to catch
similar issues in the future

Author: nstilt1

.github/workflows/chacha20.yml

@@ -213,4 +213,4 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
       - uses: RustCrypto/actions/cross-install@master
-      - run: RUSTFLAGS="${{ matrix.rustflags }}" cross test --package chacha20 --target ${{ matrix.target }}
+      - run: RUSTFLAGS="${{ matrix.rustflags }}" cross test --package chacha20 --target ${{ matrix.target }} --all-features

chacha20/src/rng.rs

@@ -362,6 +362,10 @@ macro_rules! impl_chacha_rng {
             #[inline]
             fn generate(&mut self, r: &mut Self::Results) {
                 self.0.generate(&mut r.0);
+                #[cfg(target_endian = "big")]
+                for word in r.0.iter_mut() {
+                    *word = word.to_le();
+                }
             }
         }
 
@@ -1066,7 +1070,7 @@ pub(crate) mod tests {
             tester_array = [0u8; LEN];
             dest_pos = 0;
 
-            // test fill_bytes with lengths starting at N bytes, decreasing by 1,
+            // test fill_bytes with lengths starting at `N` bytes, decreasing by 1,
             // down to 1 byte
             for test_len in 1..=N {
                 let debug_start_word_pos = rng.get_word_pos();