getopt(3) returns an int; avoid infinite loop on platforms where char is
unsigned.

Index: adplugdb/adplugdb.cpp
--- adplugdb/adplugdb.cpp.orig
+++ adplugdb/adplugdb.cpp
@@ -298,7 +298,7 @@ static void db_save(void)
 
 int main(int argc, char *argv[])
 {
-  char		opt;
+  int		opt;
   bool		dbokay;
   unsigned int	i;