Use PRId32 in c99 environment.

This issue is discussed before. It is the second try.
In case sizeof(uint32_t) != sizeof(unsigned int), we got warnings at cdump.c.
Using PRId32 macro is the best way to avoid it.
But terrible VC++ doesn't have PRId32 that is supported since C99.

This patch is to define PRId32 as "x" if the complier doesn't support C99.