Fix definition of SIG_ERR

src/header/signal/mod.rs

@@ -23,7 +23,7 @@ type SigSet = BitSet<[c_ulong; 1]>;
 
 pub const SIG_DFL: usize = 0;
 pub const SIG_IGN: usize = 1;
-pub const SIG_ERR: usize = !0;
+pub const SIG_ERR: isize = -1;
 
 pub const SIG_BLOCK: c_int = 0;
 pub const SIG_UNBLOCK: c_int = 1;