High-resolution timer issues

[James E Keenan]

config/gen/platform/generic/hires_timer.c and 
config/gen/platform/win32/hires_timer.c were committed to trunk on Sep 
06 in r41081 when the 'pluggable_runcore' branch was merged to trunk.
config/gen/platform/darwin/hires_timer.c was added a few hours later  in 
r41087 in an attempt to cope with Darwin-specific problems. More and 
more I think that there are problems with this implementation.

See the following two Trac tickets:

https://trac.parrot.org/parrot/ticket/985#comment:3 and following 
comments.  Andy Dougherty cites a number of problems or limitations of 
the implementation.

https://trac.parrot.org/parrot/ticket/989#comment:5, where I report 
SIGNAL 10 (SIGBUS) errors on Darwin/PPC subsequent to the introduction 
of darwin/hires_timer.c.  I thought they had cleared up, but then I 
noticed other Smolder reports with the same problem.  While these errors 
are intermittent, a look at our Smolder reports for Darwin suggest that 
they are happening more often than not.  I don't have any expertise in 
either high-resolution timing or diagnosis of bus errors, so I've done 
as much as I can on this ticket.

"Stability!" is supposed to be our theme of the week, especially leading 
into Tuesday's release.  But this is clearly an area of instability. 
I'm hoping that posting to the list because I fear that if these 
problems are not treated by Tuesday they will then simply get swept 
under the rug in the rush to merge in the next big branch.

Thank you very much.
kid51