The changes below work around the lack of h_error on Windows:
--- libguile/net_db.c~0 2013-03-25 23:44:46.000000000 +0200
+++ libguile/net_db.c 2013-06-13 13:30:20.448923200 +0300
@@ -55,6 +55,47 @@
#include "libguile/net_db.h"
#include "libguile/socket.h"
+#ifdef __MINGW32__
+# define h_errno WSAGetLastError()
+# define HAVE_H_ERRNO 1
+# define HAVE_HSTRERROR 1
+# ifdef HAVE_DECL_HSTRERROR
+# undef HAVE_DECL_HSTRERROR
+# endif
+# define HAVE_DECL_HSTRERROR 1
+# define HOST_NOT_FOUND WSAHOST_NOT_FOUND
+# define TRY_AGAIN WSATRY_AGAIN
+# define NO_RECOVERY WSANO_RECOVERY
+# define NO_DATA WSANO_DATA
+
+char *hstrerror (int);
+
+char *
+hstrerror (int error_no)
+{
+ static char buf[500];
+ DWORD ret;
+
+ if (error_no == 0)
+ error_no = WSAGetLastError ();
+
+ ret = FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM |
+ FORMAT_MESSAGE_IGNORE_INSERTS,
+ NULL,
+ error_no,
+ 0, /* choose most suitable language */
+ buf, sizeof (buf), NULL);
+
+ while (ret > 0 && (buf[ret - 1] == '\n' ||
+ buf[ret - 1] == '\r' ))
+ --ret;
+ buf[ret] = '\0';
+ if (!ret)
+ sprintf (buf, "Winsock error %u", error_no);
+
+ return buf;
+}
+#endif /* __MINGW32__ */
#if defined (HAVE_H_ERRNO)
/* Only wrap gethostbyname / gethostbyaddr if h_errno is available. */
