patch 9.1.1221: Wrong cursor pos when leaving Insert mode just after 'autoindent'

patch 9.1.1221: Wrong cursor pos when leaving Insert mode just after 'autoindent'

Problem:  Wrong cursor position and '^' mark when leaving Insert mode
          just after 'autoindent' and cursor on last char of line.
Solution: Don't move cursor to NUL when it wasn't moved to the left
          (zeertzjq).

fixes: #15581
related: neovim/neovim#30165 neovim/neovim#32943
closes: #16922

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>