#12 Patch to fix build error with recen gcc/ncurses

[winnie]

When I try to build this with current gcc and ncureses I'm getting followting error:

nmixer.cc:219:26: error: format not a string literal and no format arguments [-Werror=format-security]
  219 |                 mvwprintw(mixwin, my_y - 1, my_x, (char*)source);
      |                 ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Attached patch fixes this.

[winnie]

Actual patch for quick view:

--- a/nmixer/nmixer.cc   2017-05-16 01:25:18.000000000 +0300
+++ b/nmixer/nmixer.cc 2023-06-06 14:18:33.536413971 +0300
@@ -216,7 +216,7 @@
        mvwprintw(mixwin, my_y + 1, my_x, (char*)empty_scrollbar);

        //draw new bar

-       mvwprintw(mixwin, my_y - 1, my_x, (char*)source);
+       mvwprintw(mixwin, my_y - 1, my_x, "%s", (char*)source);
        if (i == currentbar)
        {
             mvwchgat(mixwin, my_y - 1, my_x, strlen(source), A_REVERSE,