MAINT: Drop twox-hash from test-nostd to fix the builder for Rust 1.36

Drop this dependency so that we don't have random rust version breaks or
other issues. We can use a simple dummy hasher instead.

Author: bluss

test-nostd/Cargo.toml

@@ -7,7 +7,5 @@ edition = "2018"
 
 [dependencies]
 indexmap = { path = "..", features = ["serde-1"] }
-# no-std compatible hasher
-twox-hash = { version = "1.5", default-features = false }
 
 [dev-dependencies]

test-nostd/src/lib.rs

@@ -1,13 +1,26 @@
 #![no_std]
 
 use core::hash::BuildHasherDefault;
+use core::hash::Hasher;
+use core::iter::FromIterator;
+
 use indexmap::IndexMap;
 use indexmap::IndexSet;
-use twox_hash::XxHash64;
-type Map<K, V> = IndexMap<K, V, BuildHasherDefault<XxHash64>>;
-type Set<T> = IndexSet<T, BuildHasherDefault<XxHash64>>;
 
-use core::iter::FromIterator;
+#[derive(Default)]
+struct BadHasher(u64);
+
+impl Hasher for BadHasher {
+    fn finish(&self) -> u64 { self.0 }
+    fn write(&mut self, bytes: &[u8]) {
+        for &byte in bytes {
+            self.0 += byte as u64
+        }
+    }
+}
+
+type Map<K, V> = IndexMap<K, V, BuildHasherDefault<BadHasher>>;
+type Set<T> = IndexSet<T, BuildHasherDefault<BadHasher>>;
 
 pub fn test_compile() {
     let mut map = Map::default();