Modified the DWARF parser for both the single DWARF file and for the case

where the DWARF is in the .o files so they can track down the actual type for
a forward declaration. This was working before for just DWARF files, but not
for DWARF in .o files where the actual definition was in another .o file.

Modified the main thread name in the driver to be more consistent with the
other LLDB thread names.

llvm-svn: 118383