Use ErrorKind::Interrupted instead of WouldBlock

std function expect std::io::ErrorKind::Interrupted to be returned
when doing blocking operations. Instead we were returning WouldBlock.

telos/src/raw.rs

@@ -60,11 +60,11 @@ impl Error for TlsError {
         &self.msg
     }
 }
-/// Convert TlsError to io::Error, use WouldBlock if applicable
+/// Convert TlsError to io::Error, use std::io::ErrorKindInterrupted if applicable
 impl convert::From<TlsError> for io::Error {
     fn from(err: TlsError) -> Self {
         match err.code {
-            ffi::WANT_POLLIN | ffi::WANT_POLLOUT => io::Error::new(io::ErrorKind::WouldBlock, err),
+            ffi::WANT_POLLIN | ffi::WANT_POLLOUT => io::Error::new(io::ErrorKind::Interrupted, err),
             _ => io::Error::new(io::ErrorKind::Other, err.msg),
         }
     }