Add (revert back) support for static libs for FFI engine.

[comm644]

Environment: We try to build application for deploying to all Linux-based distros, and for reach this goal we need decrease system dependencies.

We already have build with few dependencies (all KPHP dependencies locked to libc 2.5 other linked as static), but FFI works only with dynamic libs. It can break application deployment.

related: issue #380