If the stack size is > 4K, emit chkstk, which probes the stack to commit
the pages required to support the large stack.

Bug: swiftshader:25
Change-Id: I6b9f09218736ffb641cb1dbf95a1de7149633ef8
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41608
Presubmit-Ready: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>