editors/vim: Allow system vimrc, and include defaults.vim for vim-tiny
Two changes here (along with bumping to the latest upstream patch):
- In the previous Vim commit, support for the system-wide vimrc/gvimrc was dropped because we went through contortions to fix loading order and monkey around with various defaults.
However, many people used that file for their system. This commit re-adds support for loading it. All work for untangling the mess of loading defaults.vim and preventing circular loads is left to the user. We just support loading that file; what you do with it is your call.
- vim-tiny is supposed to be the smallest possible Vim experience, being just the binary and no runtime library. However, without a viable defaults.vim, it's essentially just a larger, slower Vi. The vim-tiny package now ships with defaults.vim, which is patched to prevent errors from Vim loading the syntax library (which is not installed).