Remove obsolete darwin dynloader code

not needed since macOS 10.3 (2003)

src/backend/port/dynloader/darwin.c

 /*
  * Dynamic loading support for macOS (Darwin)
  *
- * If dlopen() is available (Darwin 10.3 and later), we just use it.
- * Otherwise we emulate it with the older, now deprecated, NSLinkModule API.
- *
  * src/backend/port/dynloader/darwin.c
  */
 #include "postgres.h"
 
-#ifdef HAVE_DLOPEN
 #include <dlfcn.h>
-#else
-#include <mach-o/dyld.h>
-#endif
 
 #include "dynloader.h"
 
 
-#ifdef HAVE_DLOPEN
-
 void *
 pg_dlopen(const char *filename)
 {
@@ -34,7 +25,6 @@ pg_dlclose(void *handle)
 PGFunction
 pg_dlsym(void *handle, const char *funcname)
 {
-	/* Do not prepend an underscore: see dlopen(3) */
 	return dlsym(handle, funcname);
 }
 
@@ -43,96 +33,3 @@ pg_dlerror(void)
 {
 	return dlerror();
 }
-#else							/* !HAVE_DLOPEN */
-
-/*
- * These routines were taken from the Apache source, but were made
- * available with a PostgreSQL-compatible license.  Kudos Wilfredo
- * Sánchez <wsanchez@apple.com>.
- */
-
-static NSObjectFileImageReturnCode cofiff_result = NSObjectFileImageFailure;
-
-void *
-pg_dlopen(const char *filename)
-{
-	NSObjectFileImage image;
-
-	cofiff_result = NSCreateObjectFileImageFromFile(filename, &image);
-	if (cofiff_result != NSObjectFileImageSuccess)
-		return NULL;
-	return NSLinkModule(image, filename,
-						NSLINKMODULE_OPTION_BINDNOW |
-						NSLINKMODULE_OPTION_RETURN_ON_ERROR);
-}
-
-void
-pg_dlclose(void *handle)
-{
-	NSUnLinkModule(handle, NSUNLINKMODULE_OPTION_NONE);
-}
-
-PGFunction
-pg_dlsym(void *handle, const char *funcname)
-{
-	NSSymbol symbol;
-	char	   *symname = (char *) malloc(strlen(funcname) + 2);
-
-	if (!symname)
-		return NULL;
-
-	sprintf(symname, "_%s", funcname);
-	if (NSIsSymbolNameDefined(symname))
-	{
-		symbol = NSLookupAndBindSymbol(symname);
-
-		free(symname);
-		return (PGFunction) NSAddressOfSymbol(symbol);
-	}
-	else
-	{
-		free(symname);
-		return NULL;
-	}
-}
-
-char *
-pg_dlerror(void)
-{
-	NSLinkEditErrors c;
-	int			errorNumber;
-	const char *fileName;
-	const char *errorString = NULL;
-
-	switch (cofiff_result)
-	{
-		case NSObjectFileImageSuccess:
-			/* must have failed in NSLinkModule */
-			NSLinkEditError(&c, &errorNumber, &fileName, &errorString);
-			if (errorString == NULL || *errorString == '\0')
-				errorString = "unknown link-edit failure";
-			break;
-		case NSObjectFileImageFailure:
-			errorString = "failed to open object file";
-			break;
-		case NSObjectFileImageInappropriateFile:
-			errorString = "inappropriate object file";
-			break;
-		case NSObjectFileImageArch:
-			errorString = "object file is for wrong architecture";
-			break;
-		case NSObjectFileImageFormat:
-			errorString = "object file has wrong format";
-			break;
-		case NSObjectFileImageAccess:
-			errorString = "insufficient permissions for object file";
-			break;
-		default:
-			errorString = "unknown failure to open object file";
-			break;
-	}
-
-	return (char *) errorString;
-}
-
-#endif							/* HAVE_DLOPEN */