Recognize macOS 11 and later.
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=44605
https://github.com/indexdata/yazproxy/issues/21
--- configure	2022-08-18 16:32:05
+++ configure	2024-06-06 12:59:04
@@ -9083,18 +9083,13 @@
       _lt_dar_allow_undefined='$wl-undefined ${wl}suppress' ;;
     darwin1.*)
       _lt_dar_allow_undefined='$wl-flat_namespace $wl-undefined ${wl}suppress' ;;
-    darwin*) # darwin 5.x on
-      # if running on 10.5 or later, the deployment target defaults
-      # to the OS version, if on x86, and 10.4, the deployment
-      # target defaults to 10.4. Don't you love it?
-      case ${MACOSX_DEPLOYMENT_TARGET-10.0},$host in
-	10.0,*86*-darwin8*|10.0,*-darwin[912]*)
-	  _lt_dar_allow_undefined='$wl-undefined ${wl}dynamic_lookup' ;;
-	10.[012][,.]*)
-	  _lt_dar_allow_undefined='$wl-flat_namespace $wl-undefined ${wl}suppress' ;;
-	10.*|11.*)
-	  _lt_dar_allow_undefined='$wl-undefined ${wl}dynamic_lookup' ;;
-      esac
+    darwin*)
+      case ${MACOSX_DEPLOYMENT_TARGET},$host in
+    10.[012],*|,*powerpc*-darwin[5-8]*)
+      _lt_dar_allow_undefined='${wl}-flat_namespace ${wl}-undefined ${wl}suppress' ;;
+    *)
+      _lt_dar_allow_undefined='${wl}-undefined ${wl}dynamic_lookup' ;;
+      esac
     ;;
   esac
     if test yes = "$lt_cv_apple_cc_single_mod"; then