hermit: add AF_VSOCK

Author: mkroening

libc-test/semver/hermit.txt

@@ -1,6 +1,7 @@
 AF_INET
 AF_INET6
 AF_UNSPEC
+AF_VSOCK
 CLOCK_MONOTONIC
 CLOCK_REALTIME
 DT_BLK

src/hermit.rs

@@ -117,6 +117,7 @@ s! {
 pub const AF_UNSPEC: i32 = 0;
 pub const AF_INET: i32 = 0;
 pub const AF_INET6: i32 = 1;
+pub const AF_VSOCK: i32 = 2;
 
 pub const CLOCK_REALTIME: clockid_t = 1;
 pub const CLOCK_MONOTONIC: clockid_t = 4;