Enable optimize_for_size for Rust std (#8844)

Author: topjohnwu

native/src/.cargo/config.toml

@@ -8,5 +8,5 @@ target-dir = "../out/rust"
 
 [unstable]
 build-std = ["std", "panic_abort"]
-build-std-features = ["panic_immediate_abort"]
+build-std-features = ["panic_immediate_abort", "optimize_for_size"]
 profile-rustflags = true