feat(tvix): Jemalloc -> MiMalloc

Use the faster and newer MiMalloc memory allocator for all endpoints in
the workspace.

Change-Id: Ic60237284ed168e46ec6e8f28e2710bae4385c6f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12149
Tested-by: BuildkiteCI
Reviewed-by: aspen <root@gws.fyi>

tvix/build/Cargo.toml

@@ -16,6 +16,7 @@ tvix-castore = { path = "../castore" }
 tvix-tracing = { path = "../tracing" }
 tracing = "0.1.40"
 url = "2.4.0"
+mimalloc = "0.1.43"
 
 [dependencies.tonic-reflection]
 optional = true

tvix/build/src/bin/tvix-build.rs

@@ -17,6 +17,11 @@ use tvix_build::proto::FILE_DESCRIPTOR_SET;
 #[cfg(feature = "tonic-reflection")]
 use tvix_castore::proto::FILE_DESCRIPTOR_SET as CASTORE_FILE_DESCRIPTOR_SET;
 
+use mimalloc::MiMalloc;
+
+#[global_allocator]
+static GLOBAL: MiMalloc = MiMalloc;
+
 #[derive(Parser)]
 #[command(author, version, about, long_about = None)]
 struct Cli {