Our bind-tools are compiled without GSSAPI support by default. Until we
make it build with MIT Kerberos from base by default, we have to trick this
configure script into believing that "echo realm | nsupdate" works.

--- src/external/nsupdate.m4.orig	2024-01-12 12:05:40 UTC
+++ src/external/nsupdate.m4
@@ -4,13 +4,13 @@ if test -x "$NSUPDATE"; then
   AC_DEFINE_UNQUOTED([NSUPDATE_PATH], ["$NSUPDATE"], [The path to nsupdate])
   AC_MSG_RESULT(yes)
 
-  AC_MSG_CHECKING(for nsupdate 'realm' support')
-  if AC_RUN_LOG([echo realm |$NSUPDATE >&2]); then
-    AC_MSG_RESULT([yes])
-  else
-    AC_MSG_RESULT([no])
-    AC_MSG_ERROR([nsupdate does not support 'realm'])
-  fi
+  #AC_MSG_CHECKING(for nsupdate 'realm' support')
+  #if AC_RUN_LOG([echo realm |$NSUPDATE >&2]); then
+  #  AC_MSG_RESULT([yes])
+  #else
+  #  AC_MSG_RESULT([no])
+  #  AC_MSG_ERROR([nsupdate does not support 'realm'])
+  #fi
 
 else
   AC_MSG_RESULT([no])