copy and adapt code and benchmarks from rust-lang/rust#59186

Author: ssomers

Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "rust_bench_btreeset_intersection"
+version = "0.1.0"
+authors = ["Stein Somers <[email protected]>"]
+autotests = false
+autobenches = false 
+edition = "2018"
+
+[dev-dependencies]
+proptest = "0.9"
+rand = "0.6"
+rand_xorshift = "0.1"
+
+[[test]]
+name = "collectionstests"
+path = "src/tests/set.rs"
+
+[[bench]]
+name = "collectionsbenches"
+path = "src/benches/set.rs"
+