SymbolVendor/ELF is actually referenced by default by lib/Makefile on all

platforms and called in lldb.cpp while it is built only on some, excluding OSX.
There is no reason to not build it then by default on all platforms.

This fixes build on OSX using llvm configure & make scripts.

Patch (2 of 2) by Adam Strzelecki!

llvm-svn: 190945