Problem: Cannot use an autoload function from a package under start.
Solution: Also look in the "start" package directory. (Bjorn Linse,
closesvim/vim#7193)
223a950a85
Nvim already does this in do_in_cached_path(), and this change has no
effect in Nvim as Nvim removes DIP_START after do_in_cached_path().
Accidentally failed to mark as ported:
vim-patch:8.2.1731: Vim9: cannot use += to append to empty NULL list
Co-authored-by: bfredl <bjorn.linse@gmail.com>