cc.h is missing the (sn)printf formatters

LWIP_DEBUG depends on the (sn)printf formatters that are normally in cc.h.

however, in the StarterWare port, their absence casuses lots of compile errors if

LWIP_DEBUG is defined.

for reference:

/* Define (sn)printf formatters for these lwIP types */

#define X8_F "02x"

#define U16_F "hu"

#define S16_F "hd"

#define X16_F "hx"

#define U32_F "lu"

#define S32_F "ld"

#define X32_F "lx"

#define SZT_F U32_F