to make it more like other OS strings

It is only undefined when this file is included by others (like ares) and
in those cases it doesn't matter.

defines are in setup.h.

the external curl include dir.

DEBUG_THREADING_GETHOSTBYNAME is defined

operation as a size_t

it was quite a long time since he experienced that one.

use %zd when outputting size_t

make strtol() returns get stored in long variables
don't mix size_t with int

a curl_off_t type that is larger than 4 bytes