bug#13768: --without-posix code uses scm_getpid() in libguile-2.0.2

[Jan Schukat]

I'm experimenting a little with statically linking a minimal build of 
libguile. So while no one really would want to build it it with 
--without-posix (except when you want the same functionality on all 
platforms including windows in your program), and this is a low priority 
bug and I can easily fix it myself for my purposes, it is still a bug.

What happens is, in random.c in random_state_of_last_resort on line 668 
scm_getpid is used to seed the random generator. So either a 
preprocessor switch or a hand constructed scm like in scm_getpid 
(scm_from_ulong(getpid())) should be used there.

Regards