issues with current libtool.m4 in macOS 11.x

[NIIBE Yutaka]

Hello,

Aleix Conchillo Flaqué wrote:
> A few days ago I sent a patch to update libtool.m4 out of the blue.
> The reason for this update is that the current libtool.m4 doesn't
> support macOS 11.x properly which means libgcrypt is linked with the
> option flat_namespace.

Thank you for your report.  I created a ticket to track this issue:

    https://dev.gnupg.org/T5610

If our purpose is to minimize the changes of GnuPG and its friends, I
think that the change could be minimized like the following.

diff --git a/m4/libtool.m4 b/m4/libtool.m4
index 8795701..a83d3f1 100644
--- a/m4/libtool.m4
+++ b/m4/libtool.m4
@@ -1054,7 +1054,7 @@ _LT_EOF
 	  _lt_dar_allow_undefined='${wl}-undefined ${wl}dynamic_lookup' ;;
 	10.[[012]]*)
 	  _lt_dar_allow_undefined='${wl}-flat_namespace ${wl}-undefined ${wl}suppress' ;;
-	10.*)
+	10.*|11.*)
 	  _lt_dar_allow_undefined='${wl}-undefined ${wl}dynamic_lookup' ;;
       esac
     ;;
--