[Bug-gnubg] Attempt to speed up single threaded use in multi threaded build

[Jonathan Kinsey]

I've checked in a experimental change which will hopefully speed up the
single-thread evaluation in the multi-threaded build. If this works (and the
multi-thread evaluation isn't slower) we can remove the single threaded code.

Hopefully Max will create a build from this code and we can check the speed of
this compared to the recent builds. Ideally 5 tests should help this:

old single threaded build.
old multi threaded build with 1 thread.
new multi threaded build with 1 thread.
old multi threaded build with threads set to number of cores.
new multi threaded build with threads set to number of cores.

Jon

Ps. I've simplified the change from when I initially tried this a while ago
using some magic #defines, hopefully they'll work ok on linux.

---

New! Receive and respond to mail from other email accounts from within Hotmail Find out how.