message: Guard sol library
diff: # Register the sol library for parsing lua
  #------------------------------------------------------------------------------
  +if (LUA_FOUND)
  blt_add_library(NAME sol
  HEADERS sol/sol.hpp)
  @@ -26,6 +27,7 @@ install(EXPORT axom-targets DESTINATION lib/cmake)
  set(SOL_FOUND TRUE CACHE INTERNAL "")
  mark_as_advanced(SOL_FOUND)
  +endif()
  #------------------------------------------------------------------------------
  # Register the built-in CLI11 library for command line option parsing
  