hermit: make AF_INET = 3

(backport <rust-lang#4344>)
(cherry picked from commit 13ac7db)

Author: mkroening

src/hermit.rs

@@ -115,7 +115,7 @@ s! {
 }
 
 pub const AF_UNSPEC: i32 = 0;
-pub const AF_INET: i32 = 0;
+pub const AF_INET: i32 = 3;
 pub const AF_INET6: i32 = 1;
 pub const AF_VSOCK: i32 = 2;