Don't assert on mod->e_type in __libdwfl_relocate_value.

Don't assert on mod->e_type in __libdwfl_relocate_value.

When setting up the module and searching for an ELF file with a correct
build_id __libdwfl_relocate_value will be called for an ET_REL file in
__libdwfl_find_elf_build_id but mod->e_type is not yet setup in that case
because the Dwfl_Module isn't yet complete (the build-id could mismatch).
This can happen when using the dwfl_linux_kernel_find_elf callback when
it searches for the ELF file matching a kernel module.