build failure against `gcc-15` (C23 incompatibilities)

[trofi]

gcc-15 switched to C23 by default (https://gcc.gnu.org/gcc-15/porting_to.html) and broke lv building as:

../src/console.c: In function 'ConsoleGetWindowSize':
../src/console.c:218:13: error: too many arguments to function 'tgetnum'; expected 0, have 1
  218 |     WIDTH = tgetnum( "columns" );
      |             ^~~~~~~  ~~~~~~~~~
../src/console.c:113:35: note: declared here
  113 | extern int tgetent(), tgetflag(), tgetnum(), tputs();
      |                                   ^~~~~~~
...

This happens because extern int tgetnum() changed the meaning to extern int tgetnum(void).