[Oops, I forgot half of the patch.]

[Oops, I forgot half of the patch.]
Patch # 1050 by Amaury Forgeot d'Arc.
On Windows, debug builds insert stack probes, and recursive functions
tend to exhaust the stack faster.
This patch reduces the marshal maximum depth from 2000 to 1500 for debug
builds only. Optimized builds are not affected.
This allows test_marshal to pass with debug builds.