Locally restart ssh_poll() upon EINTR.

BUG: https://red.libssh.org/issues/186

Reviewed-by: Aris Adamantiadis <aris@0xbadc0de.be>
Signed-off-by: Sebastien Boving <seb@google.com>

src/poll.c

@@ -597,11 +597,17 @@ int ssh_poll_ctx_dopoll(ssh_poll_ctx ctx, int timeout) {
   ssh_poll_handle p;
   socket_t fd;
   int revents;
+  struct ssh_timestamp ts;
 
   if (!ctx->polls_used)
     return SSH_ERROR;
 
-  rc = ssh_poll(ctx->pollfds, ctx->polls_used, timeout);
+  ssh_timestamp_init(&ts);
+  do {
+    int tm = ssh_timeout_update(&ts, timeout);
+    rc = ssh_poll(ctx->pollfds, ctx->polls_used, tm);
+  } while (rc == -1 && errno == EINTR);
+
   if(rc < 0)
     return SSH_ERROR;
   if (rc == 0)