evas/cserve2: Implement shared index and buffers

evas/cserve2: Implement shared index and buffers

Only import the C file for now.
Implement the following features:

- Shared Arrays
Store arrays of elements of fixed size in shm.

- Shared Mempool
Store random sized buffers in shm.
These buffers are indexed in a Shared Array and are
referred to using their index only.

- Shared Strings
Store strings in a shm in a way similar to Eina_Stringshare
(except strings are referred to using an int index).

- Include evas_cserve2_index.c to the compilation.
- Declare shared index functions in header file.
- Call init() and shutdown() on the shared index subsystem.
- Add find and foreach functions