Update upstream slirp

Adds gitignore, README file, and fixes ident protocol parsing.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

diff --git a/slirp b/slirp
index 0e79ba4..f0da672 160000 (submodule)
--- a/slirp
+++ b/slirp
@@ -1 +1 @@
-Subproject commit 0e79ba48567ccfb3cc2cf2e98cce8811eee7e455
+Subproject commit f0da6726207b740f6101028b2992f918477a4b08