debuginfod_find_section: Always update rc with most recent error code

debuginfod_find_section: Always update rc with most recent error code

debuginfod_find_section may attempt to download both the debuginfo
and executable matching the given build-id.  If neither of these
files can be found, update rc to ensure that we always return an
accurate error code in this case.

Signed-off-by: Aaron Merey <amerey@redhat.com>