Fix simple_prompt
Fix simple_prompt

Since simple_prompt() changes its signature in v10, use a pointer
instead of a static array for password. I decided to use an static array
in commit 12698abce6bd91faecc6c0f73b078cc147674139, however, using a
pointer is easier from a portability point of view.

eulerto/pgquarrel,eulerto/pgquarrel