configure: Implement ld override whitelist

Bring `configure` into alignment with `ghc-toolchain`, ensuring that the
ld-override logic will only take effect on Linux and Windows.

Fixes #25501.

m4/find_ld.m4

@@ -79,13 +79,16 @@ AC_DEFUN([FIND_LD],[
         dnl See #21712.
         AC_CHECK_TARGET_TOOL([LD], [ld])
         ;;
-    *)
+    *-linux|*-mingw32)
         if test "x$enable_ld_override" = "xyes"; then
             find_ld
         else
             AC_CHECK_TARGET_TOOL([LD], [ld])
         fi
         ;;
+    *)
+        AC_CHECK_TARGET_TOOL([LD], [ld])
+        ;;
     esac
     CHECK_LD_COPY_BUG([$1])
 ])