fix the build error for printf argument of pid_t

Signed-off-by: tymon.huang <[email protected]>

Author: tymon.huang

src/util.c

@@ -400,7 +400,7 @@ save_pid_file(const char *pf)
     if (pf) {
         FILE *f = fopen(pf, "w");
         if (f) {
-            fprintf(f, "%zu\n", getpid());
+            fprintf(f, "%d\n", getpid());
             fclose(f);
         }
     }