zero-length arrays are not defined by standard C

[jerryyu]

{{{ In "obex_header.h", the structure obex_unicode_hdr was defined to contain an zero-length array.

struct obex_unicode_hdr {

uint8_t hi;
uint16_t hl;
uint8_t hv[0];

}

Actually, zero-length array are forbidden by standard C, although it was defined by windows C complier and gcc compiler. To push it to be cross-platform, it's better to follow the standard C.}}}

[jerryyu]

patch for this bug