[ELF] Fixed -Wunused in -asserts  mode.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@172131 91177308-0d34-0410-b5e6-96231b3b80d8
[ELF] Fix leading 0 count. Matches change in llvm.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@172132 91177308-0d34-0410-b5e6-96231b3b80d8
[ELF] Add support for __init_array_{start,end}.

With this change c++ global constructors and destructors work.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@172133 91177308-0d34-0410-b5e6-96231b3b80d8