Rebuild xhpast.exe with static linkage

Summary:
Fixes T5372.

This thing is like 2.5MB but surely we will never regret checking multi-megabyte binaries into the VCS.

Test Plan:

• Observed static flags being used during build.
• Ran xhpast.exe with some PHP piped into it.
• Saw large binary size.

Reviewers: richardvanvelzen

Reviewed By: richardvanvelzen

Subscribers: epriestley

Maniphest Tasks: T5372

Differential Revision: https://secure.phabricator.com/D9581