CTags calls the function declarations prototypes, so awk for that instead of "function"
Remove ffi-cdecl subdirectory and build directly in main dir
Some structs use sigval from the C API, so define that

This cannot be defined on demand in the individual E FFI modules,
 because that would redefine the union, which makes LuaJIT unhappy.
Ignore Ecore_Wayland.h, because it needs some additional Wayland structs