Fixed issues with the way ELF symbols are parsed:

- Do not add symbols with no names
- Make sure that symbols from ELF symbol tables know that the byte size is correct. Previously the symbols would calculate their sizes by looking for the next symbol and take symbols that had zero size and make them have invalid sizes.
- Added the ability to dump raw ELF symbols by adding a Dump method to ELFSymbol

Also removed some unused code from lldb_private::Symtab.

llvm-svn: 179466