Every arch now bears the burden of sanitizing CLONE_IDLETASK out of the
clone_flags passed to do_fork() by userspace.  This patch hoists the
masking of CLONE_IDLETASK out of the system call entrypoints into
do_fork(), and thereby removes some small overheads from do_fork(), as
do_fork() may now assume that CLONE_IDLETASK has been cleared.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>