$NetBSD$

Fix shell compatibility warning.

--- libraries/ilmbase/bootstrap.orig	2021-07-08 09:56:01.000000000 +0000
+++ libraries/ilmbase/bootstrap
@@ -1,7 +1,7 @@
 #! /bin/sh
 # If we're on OS X, use glibtoolize instead of toolize when available
 HOSTTYPE=`uname`
-if [ "$HOSTTYPE" == "Darwin" ] && $(which glibtoolize > /dev/null 2>&1) ; then
+if [ "$HOSTTYPE" = "Darwin" ] && $(which glibtoolize > /dev/null 2>&1) ; then
         LIBTOOLIZE=glibtoolize
 else
         LIBTOOLIZE=libtoolize