[klibc] Move architecture-specific initialization to arch/

Move out architecture-specific initialization code (currently only for
i386) into the arch/ directory and define a configuration variable
_KLIBC_HAS_ARCHINIT to indicate its presence.

For consistency, change __init_stdio() to __libc_init_stdio().

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
6 files changed