[PATCH] [ELF] Make -init/-fini options compatible with the gnu linker

[Simon Atanasyan]

>>! In D6578#9, @shankar.easwaran wrote:
> $ ld.gold --help|grep ctors
>   --ctors-in-init-array       Use DT_INIT_ARRAY for all constructors (default)
>   --no-ctors-in-init-array    Handle constructors as directed by compiler.
> 
> If this is the case I recommend using old code so that ctors and init/fini are placed in init array sections or fini array sections.

The old code puts to the `.init_array/.fini_array` sections only the symbols specified by the `-init/-fini` command line options. It does nothing with incoming `.ctors` and `.init` sections. I can keep `xxxInitAtom / xxxFiniAtom` classes but they will be a really dead code. Sure we can/need to implement `--ctors-in-init-array` default semantics. But I think it is a separate task.

http://reviews.llvm.org/D6578