libdwfl: Make dwfl_linux_proc_attach work even without any Dwfl_Modules.

dwfl_linux_proc_attach depended on a Dwfl_Module with the correct
ELF header already being available. That isn't really necessary since
when we attach we have the main exe ELF file available. Just use that
to make dwfl_linux_proc_attach always work.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
6 files changed