merkle-tree: Use matches crate when targeting eBPF

Cargo.lock

@@ -4792,6 +4792,7 @@ version = "1.7.0"
 dependencies = [
  "fast-math",
  "hex",
+ "matches",
  "solana-program 1.7.0",
 ]
 

merkle-tree/Cargo.toml

@@ -13,6 +13,10 @@ edition = "2018"
 solana-program = { path = "../sdk/program", version = "=1.7.0" }
 fast-math = "0.1"
 
+# This can go once the BPF toolchain target Rust 1.42.0+
+[target.bpfel-unknown-unknown.dependencies]
+matches = "0.1.8"
+
 [dev-dependencies]
 hex = "0.4.2"
 

merkle-tree/src/lib.rs

@@ -1,3 +1,8 @@
 #![allow(clippy::integer_arithmetic)]
+
+#[cfg(target_arch = "bpf")]
+#[macro_use]
+extern crate matches;
+
 pub mod merkle_tree;
 pub use merkle_tree::MerkleTree;