Bump version dep on libc

Author: alexcrichton

Cargo.toml

@@ -33,7 +33,7 @@ memmap = { version = "0.7.0", optional = true }
 object = { version = "0.9.0", optional = true }
 
 [target.'cfg(unix)'.dependencies]
-libc = { version = "0.2", default-features = false }
+libc = { version = "0.2.45", default-features = false }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3.3", features = ["dbghelp", "processthreadsapi", "winnt", "minwindef"] }