This files are required for compiling newlib for fool os.
They go into this dir or similar..: ~/Downloads/newlib-foolos/newlib/libc/sys/foolos 

I prefer to just link them and keep here.

configure.in
Makefile.am

syscall.h
syscall.s

syscalls.h
syscalls.c

crt0.h
crt0.s

sys/