Fixed several 64-bit porting issues

1. Use "%zu" instead of "%d" for size_t in printf
2. Variable precision specifier (eg. "%.*s") in printf should be of type int.
   (iov_len is size_t which is 64-bit when compiled with -m64)
3. Use PRId64 instead of "%lld" to print variables of type int64_t

Change-Id: I2be40a6514b5dffa0038d62b9bccc3401b8756e6