pacvim: always use "%s"-style format for printf()-style functions

[trofi]

ncuses-6.3 added printf-style function attributes and now makes
it easier to catch cases when user input is used in palce of format
string when built with CFLAGS=-Werror=format-security:

src/helperFns.cpp:103:17:
  error: format not a string literal and no format arguments [-Werror=format-security]
  103 |         mvprintw(TOP+5, 0, (x).c_str());
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

Let's wrap all the missing places with "%s" format.

[TamaMcGlinn]

I've merged this in my fork, I'm merging everything that works and doesn't change the game too much.