[ELF] - Basic versioned symbols support implemented.

Patch implements basic support of versioned symbols.
There is no wildcards patterns matching except local: *;
There is no support for hierarchies.
There is no support for symbols overrides (@ vs @@ not handled).

This patch allows programs that using simple scripts to link and run.

Differential revision: http://reviews.llvm.org/D21018

llvm-svn: 273143