Removes the STACK_GUARD_PAGE define and makes all of its code always compiled.
Implements stack overflow detection on UNIX by using a guard page at the bottom of the stack. Adds a new label on a crash that distinguishes a stack overflow from a general crash. Adds a new option -stack_guard_pages covering this feature along with a new test.
Does not support the feature on Windows where the kernel and -vm_reserve end up not working well together: i#2595 covers addressing that.
Fixes #2592 (closed)