Config.in: Introduce symbol for arches with deprecated syscalls

Config.in: Introduce symbol for arches with deprecated syscalls

Linuxthreads(old and new) need deprecated syscalls to build. Existing
architectures support these system calls but new architectures don't.
This symbol has no functional change apart from hidding the Linuxthreads
symbols from arches that don't support them.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>