Normal service has resumed after the recent instability due to 64-bit work.

CogVM binaries as per VMMaker.oscog-eem.956/r3148

Fix regression in primitive[SmallFloat]Truncated

Fix some warnings and some 64-bit issues with the ThreadedFFIPlugin.

Fix positive64BitIntegerFor: by fixing new generateSignedShiftRight:on:indent:.

Symptom is LargePositiveInteger results from primGetPosition: for SmallInteger

values.