binutils bfd/archive.c errno handling around strtol for thin archives

In binutils' BFD archive parser, get_extended_arelt_filename() parses an extended name table index using strtol() and checks errno. It then parses a thin-archive nested-origin value after ':' with strtol(endp+1, NULL, 10) without resetting errno beforehand and without validating full-string consumption. This can lead to inconsistent handling of malformed archive numeric fields.