linux: Use libc::GRND_NONBLOCK (#29)

We don't need to define this ourself. Introduced in libc 0.2.34:
  See: rust-lang/libc#830

Author: josephlr

Cargo.toml

@@ -21,7 +21,7 @@ members = ["tests/wasm_bindgen"]
 log = { version = "0.4", optional = true }
 
 [target.'cfg(unix)'.dependencies]
-libc = "0.2.29"
+libc = "0.2.34"
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3.6", features = ["minwindef", "ntsecapi", "winnt"] }

src/linux_android.rs

@@ -17,7 +17,6 @@ use core::num::NonZeroU32;
 use core::sync::atomic::{AtomicBool, Ordering};
 
 // This flag tells getrandom() to return EAGAIN instead of blocking.
-const GRND_NONBLOCK: libc::c_uint = 0x0001;
 static RNG_INIT: AtomicBool = AtomicBool::new(false);
 
 enum RngSource {
@@ -30,7 +29,7 @@ thread_local!(
 );
 
 fn syscall_getrandom(dest: &mut [u8], block: bool) -> Result<(), io::Error> {
-    let flags = if block { 0 } else { GRND_NONBLOCK };
+    let flags = if block { 0 } else { libc::GRND_NONBLOCK };
     let ret = unsafe {
         libc::syscall(libc::SYS_getrandom, dest.as_mut_ptr(), dest.len(), flags)
     };