Introduce serialport_config()

This allows to easily reconfigure a serial port as needed in
the Bus Pirate speedup patch.

Corresponding to flashrom svn r1717.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
diff --git a/programmer.h b/programmer.h
index f9f5241..3b1f03a 100644
--- a/programmer.h
+++ b/programmer.h
@@ -660,6 +660,7 @@
 
 void sp_flush_incoming(void);
 fdtype sp_openserport(char *dev, unsigned int baud);
+int serialport_config(fdtype fd, unsigned int baud);
 void __attribute__((noreturn)) sp_die(char *msg);
 extern fdtype sp_fd;
 /* expose serialport_shutdown as it's currently used by buspirate */