next_set_end even if the end symbol is being discarded.
* gasp.c: Add ATTRIBUTE_UNUSED as needed for non-BFD_ASSEMBLER.
* output-file.c, symbols.c, config/tc-i386.c: Likewise.
* config/obj-coff.c: Likewise.
(seg_info_type): Remove.
(seg_info_off_by_4): Change to array of segT.
(s_get_segment): Adjust accordingly.
(obj_pseudo_table): Fully initialize sentinel entry.