slirp: replace most qemu socket utilities with slirp own version

qemu_set_nonblock() is slightly more problematic and will be dealt
with in a separate patch.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
diff --git a/slirp/Makefile.objs b/slirp/Makefile.objs
index 959558c..d2ead94 100644
--- a/slirp/Makefile.objs
+++ b/slirp/Makefile.objs
@@ -27,6 +27,7 @@
 	tftp.o \
 	udp.o \
 	udp6.o \
+	util.o \
 	$(NULL)
 
-slirp.mo-cflags = -DG_LOG_DOMAIN=\"Slirp\"
+slirp.mo-cflags = -DG_LOG_DOMAIN=\"Slirp\" -DWITH_QEMU