Build fails on OSX Lion

[Bjoern Kerler]

In serial.c, just change :
between 
#include <sys/stat.h>
and
#include <osmocom/core/serial.h>

to the following :

//#include <linux/serial.h>
#define TIOCGSERIAL     0x541E
#define TIOCSSERIAL     0x541F
#define ASYNC_SPD_CUST  0x0030  /* Use user-specified divisor */
#define ASYNC_LOW_LATENCY 0x2000 /* Request low latency behaviour */

 struct serial_struct {
          int     type;
          int     line;
          unsigned int    port;
          int     irq;
          int     flags;
          int     xmit_fifo_size;
          int     custom_divisor;
          int     baud_base;
          unsigned short  close_delay;
          char    io_type;
          char    reserved_char[1];
          int     hub6;
          unsigned short  closing_wait; /* time to wait before closing */
          unsigned short  closing_wait2; /* no longer used... */
          unsigned char   *iomem_base;
          unsigned short  iomem_reg_shift;
          unsigned int    port_high;
          int     reserved[1];
 };