re-integrate nextstep dynloader functionality

From: Jacek Lasecki <jacek@sound.eti.pg.gda.pl>

src/backend/port/nextstep/dynloader.c

@@ -1,81 +0,0 @@
-#include <mach-o/rld.h>
-#include <streams/streams.h>
-#include <stdlib.h>
-
-static char *lastError = NULL;
-
-static NXStream *
-OpenError()
-{
-	return NXOpenMemory(NULL, 0, NX_WRITEONLY);
-}
-
-static void
-CloseError(NXStream * s)
-{
-	if (s)
-		NXCloseMemory(s, NX_FREEBUFFER);
-}
-
-static void
-TransferError(NXStream * s)
-{
-	char	   *buffer;
-	int			len,
-				maxlen;
-
-	if (lastError)
-		free(lastError);
-	NXGetMemoryBuffer(s, &buffer, &len, &maxlen);
-	lastError = malloc(len + 1);
-	strcpy(lastError, buffer);
-}
-
-void *
-next_dlopen(char *name)
-{
-	int			rld_success;
-	NXStream   *errorStream;
-	char	   *result = NULL;
-	char	  **p;
-
-	errorStream = OpenError();
-	p = calloc(2, sizeof(void *));
-	p[0] = name;
-	rld_success = rld_load(errorStream, NULL, p, NULL);
-	free(p);
-
-	if (!rld_success)
-	{
-		TransferError(errorStream);
-		result = (char *) 1;
-	}
-	CloseError(errorStream);
-	return result;
-}
-
-int
-next_dlclose(void *handle)
-{
-	return 0;
-}
-
-void *
-next_dlsym(void *handle, char *symbol)
-{
-	NXStream   *errorStream = OpenError();
-	char		symbuf[1024];
-	unsigned long symref = 0;
-
-	sprintf(symbuf, "_%s", symbol);
-	if (!rld_lookup(errorStream, symbuf, &symref))
-		TransferError(errorStream);
-	CloseError(errorStream);
-	return (void *) symref;
-}
-
-char *
-next_dlerror(void)
-{
-	return lastError;
-}

src/backend/port/nextstep/port-protos.h

@@ -1,27 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * port-protos.h--
- *	  port-specific prototypes for NeXT
- *
-
--------------------------------------------------------------------------
- */
-#ifndef PORT_PROTOS_H
-#define PORT_PROTOS_H
-
-#include "fmgr.h"				/* for func_ptr */
-#include "utils/dynamic_loader.h"
-
-void	   *next_dlopen(char *name);
-int			next_dlclose(void *handle);
-void	   *next_dlsym(void *handle, char *symbol);
-char	   *next_dlerror(void);
-
-#define pg_dlopen(f)	next_dlopen
-#define pg_dlsym		next_dlsym
-#define pg_dlclose		next_dlclose
-#define pg_dlerror		next_dlerror
-
-/* port.c */
-
-#endif							/* PORT_PROTOS_H */