Bump dep libc to v0.2.121

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

Author: NobodyXu

Cargo.toml

@@ -41,7 +41,7 @@ shell-escape = "0.1.5"
 tokio = { version = "1", features = [ "process", "io-util", "macros" ] }
 tokio-pipe = "0.2.11"
 
-libc = "0.2.112"
+libc = "0.2.121"
 io-lifetimes = "0.6"
 
 once_cell = "1.10.0"