implement dn_skipname (legacy resolver function)

src/network/dn_skipname.c

@@ -0,0 +1,12 @@
+#include <resolv.h>
+
+int dn_skipname(const unsigned char *s, const unsigned char *end)
+{
+	const unsigned char *p;
+	for (p=s; p<end; p++)
+		if (!*p) return p-s+1;
+		else if (*p>=192)
+			if (p+1<end) return p-s+2;
+			else break;
+	return -1;
+}