1.0.41.41: tests: Fix tests for ppc-threading changes.

1.0.41.41: tests: Fix tests for ppc-threading changes.

  * The variable current_control_stack_pointer is no longer valid
on threaded targets.  Substitute thread_control_stack_size, which
is valid on all targets, fixing alien.impure.lisp.

  * Some dynamic-extent tests currently fail on threaded PPC.
Updated :fails-on information in dynamic-extent.impure.lisp.

  * Test (:timer :parallel-unschedule) locked up my linux/ppc box
when running.  Disabled, fixing timer.impure.lisp.  Interestingly,
while the lockup in question killed the keyboard and the mouse,
briefly pressing the power button caused backlogged events to be
processed, and repeatedly pressing the power button eventually
unlocked the system completely.

  * Test (:interrupt-thread :interrupt-consing-child :again) uses
sb-kernel:*pseudo-atomic-bits*, which is an x86oid-only symbol
(other ports use various parts of reg_ALLOC instead).  Disabled the
test on non-x86oid ports, fixing threads.impure.lisp.