CYGPKG_CPULOAD fixes

[John Dallaway]

Lars Povlsen wrote:

> Here's a small fix to the cpuload package (and idle thread).
> 
> In short, a missing 'volatile' attribute to the loop counter causes
> newer (arm-eabi GCC 4.2.3/eCosentric toolchain) to produce wrong
> results.
> 
> This patch adds a volatile modifier to idle_thread_loops[], and updates
> the reference to it from the cpuload package. (which was also using a
> non-array declaration).

This all seems reasonable. Presumably GCC 4 is holding the idle loop
count in a register. Any other comments before I check this in?

John Dallaway
eCos maintainer