Write 'Hello, world!' as shared object library

[midenok]

1. Create 2 files:

main.c that will contain main() func.
libhello.c that will contain hello() func. This func prints Hello, world! to terminal screen.

1. Compile libhello.c as libhello.so;
2. call hello() from main();
3. Compile main.c as main and link it with libhello.so;
4. Run main and observe output.