* elf32-s390.c (s390_elf_ldisp_reloc): New prototype.
(s390_tls_reloc): New function.
(elf_howto_table): Add long displacement relocations R_390_20,
R_390_GOT20, R_390_GOTPLT20 and R_390_TLS_GOTIE20.
(elf_s390_reloc_type_lookup): Likewise.
(elf_s390_check_relocs): Likewise.
(elf_s390_gc_sweep_hook): Likewise.
(elf_s390_relocate_section): Likewise.
* elf64-s390.c: Same changes as for elf32-s390.c.
* reloc.c: Add long displacement relocations BFD_RELOC_390_20,
BFD_RELOC_390_GOT20, BFD_RELOC_390_GOTPLT20 and
BFD_RELOC_390_TLS_GOTIE20.
* bfd-in2.h: Regenerate.
* libbfd.h: Likewise.