Add -debug flag to hdiutil to figure out packaging failures on MacOS

Author: tobbi

mk/cmake/SuperTux/BuildCPack.cmake

@@ -54,6 +54,7 @@ set(CPACK_PACKAGE_DESCRIPTION_FILE "${CMAKE_CURRENT_SOURCE_DIR}/README.md")
 set(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_CURRENT_SOURCE_DIR}/LICENSE.txt")
 set(CPACK_PACKAGE_VERSION_MAJOR ${SUPERTUX_VERSION_MAJOR})
 set(CPACK_PACKAGE_VERSION_MINOR ${SUPERTUX_VERSION_MINOR})
+set(CPACK_COMMAND_HDIUTIL "${CPACK_COMMAND_HDIUTIL} -debug")
 
 if(SUPERTUX_VERSION_TWEAK)
   set(CPACK_PACKAGE_VERSION_PATCH "${SUPERTUX_VERSION_PATCH}.${SUPERTUX_VERSION_TWEAK}")