Installing gtk 1.2 (package name gtk1) with macports chokes on the final make, in libintl.h line 440.
extern locale_t libintl_newlocale (junk, stuff, stuff)
The compiler can't find locale_t, and I'm not doing any better.
The file imports locale.h, which doesn't exist, and xlocale.h, which doesn't define this type.
Where should locale_t be defined? This might be as easy as a missed dependency, but I don't know what is missing.
By request, here is xlocale.h, minus the copyright, which is the Open Group's.
#include <X11/Xfuncproto.h>
#include <X11/Xosdefs.h>
#ifndef X_LOCALE
#include <locale.h>
#else
#define LC_ALL 0
#define LC_COLLATE 1
#define LC_CTYPE 2
#define LC_MONETARY 3
#define LC_NUMERIC 4
#define LC_TIME 5
_XFUNCPROTOBEGIN
extern char *_Xsetlocale(
int /* category */,
_Xconst char* /* name */
);
_XFUNCPROTOEND
#define setlocale _Xsetlocale
#include <stddef.h>
#endif /* X_LOCALE */
If you don't need messages translated to languages other than English, you can find various dummy versions of libintl which serve as drop-in replacements. If I remember correctly, uclibc includes one. You could also just add typedef void *locale_t; somewhere and work around the bug.
..and this is a bug. locale_t was not added to POSIX until POSIX 2008, which is a good bit newer than libgtk1.2; until then, it was a GNU extension. And in any case, since it's a very new and not-widely-supported feature, configure should be testing for it and only using it if it's present.