Fix compilation errors reported by GCC 15.2

[FeralChild64]

I'm getting the following errors when compiling zmac with GCC 15.2 as a part of the https://github.com/MEGA65/open-roms project:

3rdparty/zmac/src/zmac.y: In function ‘delayed_list’:
3rdparty/zmac/src/zmac.y:1471:9: error: too many arguments to function ‘bookmark’; expected 0, have 1
 1471 |         bookmark(delay);
      |         ^~~~~~~~ ~~~~~
3rdparty/zmac/src/zmac.y:721:6: note: declared here
  721 | void bookmark();
      |      ^~~~~~~~
3rdparty/zmac/src/zmac.y: In function ‘delayed_list1’:
3rdparty/zmac/src/zmac.y:1750:9: error: too many arguments to function ‘bookmark’; expected 0, have 1
 1750 |         bookmark(delay);
      |         ^~~~~~~~ ~~~~~
3rdparty/zmac/src/zmac.y:721:6: note: declared here
  721 | void bookmark();
      |      ^~~~~~~~
3rdparty/zmac/src/zmac.y: In function ‘nextchar’:
3rdparty/zmac/src/zmac.y:5735:59: error: too many arguments to function ‘getlocal’; expected 0, have 2
 5735 |                                         strcpy((char *)p, getlocal(ch, est[TEMPNUM].value));
      |                                                           ^~~~~~~~ ~~
3rdparty/zmac/src/zmac.y:5642:15: note: declared here
 5642 |         char *getlocal();
      |               ^~~~~~~~
3rdparty/zmac/src/zmac.y: At top level:
3rdparty/zmac/src/zmac.y:7952:7: error: conflicting types for ‘getlocal’; have ‘char *(int,  int)’
 7952 | char *getlocal(int c, int n)
      |       ^~~~~~~~
3rdparty/zmac/src/zmac.y:5642:15: note: previous declaration of ‘getlocal’ with type ‘char *(void)’
 5642 |         char *getlocal();
      |               ^~~~~~~~
3rdparty/zmac/src/zmac.y:8325:6: error: conflicting types for ‘bookmark’; have ‘void(int)’
 8325 | void bookmark(int delay)
      |      ^~~~~~~~
3rdparty/zmac/src/zmac.y:721:6: note: previous declaration of ‘bookmark’ with type ‘void(void)’
  721 | void bookmark();
      |      ^~~~~~~~

This PR fixes the errors above.