CONTRIB: debug: split poll from flags

Now poll is its own project and doesn't share the "flags" Makefile
any more. One of the issues was that it was making references to the
haproxy include path which is not needed here.
diff --git a/contrib/poll/Makefile b/contrib/poll/Makefile
new file mode 100644
index 0000000..fdee514
--- /dev/null
+++ b/contrib/poll/Makefile
@@ -0,0 +1,11 @@
+CC       = cc
+OPTIMIZE = -O2 -g
+DEFINE   =
+INCLUDE  =
+OBJS     = poll
+
+poll: poll.c
+	$(CC) $(OPTIMIZE) $(DEFINE) $(INCLUDE) -o $@ $^
+
+clean:
+	rm -f $(OBJS) *.[oas] *~