gai_strerror on mingw32

[Simon Josefsson]

Hi!  Mingw32 contains in ws2tcpip.h:

static __inline char*
gai_strerrorA(int ecode)
...
#define gai_strerror gai_strerrorA

Thus, the following test in getaddrinfo.m4 will incorrectly return 'no':

  AC_REPLACE_FUNCS(gai_strerror)

since the function isn't in any library.

How about the following patch?  Tested on mingw32 and x86 debian in
Gnutls.

/Simon

--- getaddrinfo.m4      10 Aug 2006 21:17:56 +0200      1.18
+++ getaddrinfo.m4      27 Jun 2007 13:11:06 +0200      
@@ -1,5 +1,5 @@
-# getaddrinfo.m4 serial 11
-dnl Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
+# getaddrinfo.m4 serial 12
+dnl Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -28,7 +28,19 @@
     fi
     ])
 
-  AC_REPLACE_FUNCS(gai_strerror)
+  # We can't use AC_REPLACE_FUNCS here because gai_strerror may be an
+  # inline function declared in ws2tcpip.h, so we need to get that
+  # header included somehow.
+  AC_MSG_CHECKING([for gai_strerror (possibly via ws2tcpip.h)])
+  AC_TRY_LINK([
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+], [gai_strerror (0);],
+  AC_MSG_RESULT([yes]),
+  [AC_MSG_RESULT([no])
+   AC_LIBOBJ(gai_strerror)])
+
   gl_PREREQ_GETADDRINFO
 ])