Build failure on Fedora 42/x86_64 and GCC 15

[bdwheele]

Building on the aforementioned OS/compiler combo fails with some forward declarations not matching their argument lists. Changing the declaration to match results in a successful build:

$ git diff
diff --git a/third_party/zmac/zmac.y b/third_party/zmac/zmac.y
index 81dea03..e0ad533 100644
--- a/third_party/zmac/zmac.y
+++ b/third_party/zmac/zmac.y
@@ -733,7 +733,7 @@ void putout(int value);
 int outrec;
 int outlen;
 unsigned char outbuf[1024 * 1024];
-void bookmark();
+void bookmark(int);
 void listfrombookmark();
 
 
@@ -5820,7 +5820,7 @@ int nextchar()
 {
        int c, ch;
        unsigned char *p;
-       char *getlocal();
+       char *getlocal(int, int);
 
        if (peekc != NOPEEK) {
                c = peekc;