cmake: on macOS fix dmg generation race condition

  On macOS 13, generation of the dmg distribution file intermidittenly
  fails due to a "hdiutil: create failed - Resource busy" issue. Work
  around this issue by creating a script that repeatedly attempts to
  run hdiutil until success or 15 failures.

  Thank you for contributing to MythTV!

  Please review the checklist below to ensure that your contribution
  to MythTV is ready for review by our developers.

  It is helpful to regularly rebase your pull request to ensure changes
  apply cleanly to the current MythTV development branch.

platform/darwin/CMakeLists.txt

@@ -498,6 +498,7 @@ if(DARWIN_GENERATE_DISTRIBUTION)
   set(CPACK_INSTALL_PREFIX / )
   set(CPACK_PACKAGING_INSTALL_PREFIX "${APP_NAME}.app")
   set(CPACK_MONOLITHIC_INSTALL TRUE)
+  set(CPACK_COMMAND_HDIUTIL "${CMAKE_CURRENT_LIST_DIR}/hdiutil_repeat.zsh")
 
   # Custom Inputs to Bundle
   set(CPACK_BUNDLE_NAME ${APP_NAME})

platform/darwin/hdiutil_repeat.zsh

@@ -0,0 +1,19 @@
+#!/bin/zsh
+
+if [ "$1" != "create" ]; then
+  # run normally in not an `hdiutil create` command
+  hdiutil "$@"
+  exit 0
+fi
+
+# On macOS 13, a race condition may present where hdiutil is unable to
+# write to the filesystem during an `hdiutil create` command.  Attempt
+# to work around this by attempting to build up to 15 times.
+COUNTER=0
+until /usr/bin/hdiutil "$@"; do
+  if [ $i -eq 15 ]; then
+    exit 1;
+  fi
+  let COUNTER+=1
+  sleep 2
+done