removed a warning

Rev: src/error.c:1.5
Rev: src/gc.c:1.4

src/error.c

@@ -91,7 +91,7 @@ void va_error(char *fmt, va_list args)
     abort();
   }
 
-  if(strlen(buf) >= sizeof(buf))
+  if((long)strlen(buf) >= (long)sizeof(buf))
     fatal("Buffer overflow in error()\n");
   
   push_string(make_shared_string(buf));

src/gc.c

@@ -167,7 +167,7 @@ static INT32 hashprimes[] =
   2147483647,/* ~ 2^31 = 2147483648 */
 };
 
-void do_gc()
+void do_gc(void)
 {
   double tmp;
   INT32 tmp2;