Use mimalloc when targeting musl

Also removes the armv7 linux build.
If you used it, let me know!

nodtool/Cargo.toml

@@ -43,6 +43,9 @@ xxhash-rust = { version = "0.8", features = ["xxh64"] }
 zerocopy = { version = "0.7", features = ["alloc", "derive"] }
 zstd = "0.13"
 
+[target.'cfg(target_env = "musl")'.dependencies]
+mimalloc = "0.1"
+
 [build-dependencies]
 hex = { version = "0.4", features = ["serde"] }
 quick-xml = { version = "0.36", features = ["serialize"] }

nodtool/src/main.rs

@@ -1,5 +1,11 @@
 mod argp_version;
 
+// musl's allocator is very slow, so use mimalloc when targeting musl.
+// Otherwise, use the system allocator to avoid extra code size.
+#[cfg(target_env = "musl")]
+#[global_allocator]
+static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 use std::{env, error::Error, ffi::OsStr, fmt, path::PathBuf, str::FromStr};
 
 use argp::{FromArgValue, FromArgs};