Support linux musl target for proto

Author: dzbarsky

MODULE.bazel

@@ -81,10 +81,12 @@ crate.from_cargo(
     cargo_toml = "//rs/private/prost:Cargo.toml",
     platform_triples = [
         "aarch64-unknown-linux-gnu",
+        "aarch64-unknown-linux-musl",
         "aarch64-apple-darwin",
         "aarch64-pc-windows-gnullvm",
         "aarch64-pc-windows-msvc",
         "x86_64-unknown-linux-gnu",
+        "x86_64-unknown-linux-musl",
         "x86_64-apple-darwin",
         "x86_64-pc-windows-gnullvm",
         "x86_64-pc-windows-msvc",