"expected a type specifier" error for Lwip in OMAPL138

Hi,

I am trying the Lwip example for OMAPL138. I got some errors.  For instance, one error is from C:/ti/OMAPL138_StarterWare_1_10_04_01/third_party/lwip-1.3.2/src/include/ipv4/lwip/ip_addr.h" ,error #80: expected a type specifier. 

The struct generating the error in ip_addr.h is :

PACK_STRUCT_BEGIN
struct ip_addr {
  PACK_STRUCT_FIELD(u32_t addr);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END

I have no idea of these errors. Can someone give some hints?

Thanks!

Jian