Whether a brainfart or a mismerge, I inadvertently broke PA-RISC during
the fork_by_hand()/init_idle() consolidation.

The following patch repairs a compilebug/thinko pair, consisting of the
use of an undeclared variable cpunum, and not attempting fork_idle()
until after the check for IS_ERR(idle) reported by James Bottomley.
Signed-off-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>