ffi: calling C functions

Inlining C function calls is probably broken. Needs to be confirmed and investigated (easiest would be building without dffi).

changed milestone to %ECL 16.2.0

this issue doesn't have steps to reproduce nor acceptance criteria. Inlining C function calls works fine, but we need to be more exact with pointers (we treat all pointers as void*, but today compilers will signal condition if different type, say int*, was declared earlier. This is mentioned in other task.

closed