Remove obsolete files for unused ports.

These were removed from upstream years ago already, but were left over in
GPDB for some reason. GPDB never supported these.

src/backend/port/dynloader/nextstep.c

-/* src/backend/port/dynloader/nextstep.c */
-
-#include "postgres.h"
-
-#include "mach-o/rld.h"
-#include "streams/streams.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);
-	if(!lastError)
-		ereport(ERROR, errcode(ERRCODE_OUT_OF_MEMORY),
-			errmsg("Transer error failed: out of memory"));
-
-	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;
-
-	snprintf(symbuf, sizeof(symbuf), "_%s", symbol);
-	if (!rld_lookup(errorStream, symbuf, &symref))
-		TransferError(errorStream);
-	CloseError(errorStream);
-	return (void *) symref;
-}
-
-char *
-next_dlerror(void)
-{
-	return lastError;
-}

src/template/bsdi

-case $host_os in
-  bsdi2.0 | bsdi2.1 | bsdi3*) CC=gcc2;;
-esac

src/template/dgux

-# src/template/dgux

src/template/nextstep

-# src/template/nextstep
-
-AROPT=rc
-SHARED_LIB=
-DLSUFFIX=.o

src/template/univel

-CFLAGS="-v -O -K i486,host,inline,loop_unroll -Dsvr4"
-LIBS="-lc89"