Support macOS 11 linking

[timj]

Currently we have to patch the AST package when building the conda package because the configure script doesn't know about macOS11 (see conda-forge/starlink-ast-feedstock#15). I imagine what we need to do is apply this somewhere to the Starlink automake/autoconf/libtool package(s) so that the AST distribution gets a properly functioning configure script. I can't actually remember which file should be patched. The diff itself is trivial:

--- configure.orig  2021-01-07 07:54:19.000000000 -0800
+++ configure   2021-01-07 08:31:05.000000000 -0800
@@ -671,6 +671,7 @@
 PREDIST
 STAR_SOURCE_ROOT_DIR
 GIT
+cross_compiling
 STAR_MANIFEST_DIR
 PACKAGE_VERSION_INTEGER
 PACKAGE_VERSION_RELEASE
@@ -7725,7 +7726,7 @@
      _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
     ;;

[timj]

Maybe it should be patched in autotools/libtool/libtool/libltdl/m4/libtool.m4 ?

[timj]

Ignore me. This was actually fixed a few months back but I was looking at an old checkout :-)