Add OpenVMS extensions.

    Add OpenVMS extensions.
        * ia64.h (SHF_IA_64_VMS_GLOBAL, SHF_IA_64_VMS_OVERLAID)
        (SHF_IA_64_VMS_SHARED, SHF_IA_64_VMS_VECTOR)
        (SHF_IA_64_VMS_ALLOC_64BIT, SHF_IA_64_VMS_PROTECTED)
        (SHT_IA_64_VMS_TRACE, SHT_IA_64_VMS_TIE_SIGNATURES)
        (SHT_IA_64_VMS_DEBUG, SHT_IA_64_VMS_DEBUG_STR)
        (SHT_IA_64_VMS_LINKAGES, SHT_IA_64_VMS_SYMBOL_VECTOR)
        (SHT_IA_64_VMS_FIXUP, DT_IA_64_VMS_SUBTYPE)
        (DT_IA_64_VMS_IMGIOCNT, DT_IA_64_VMS_LNKFLAGS)
        (DT_IA_64_VMS_VIR_MEM_BLK_SIZ, DT_IA_64_VMS_IDENT)
        (DT_IA_64_VMS_NEEDED_IDENT, DT_IA_64_VMS_IMG_RELA_CNT)
        (DT_IA_64_VMS_SEG_RELA_CNT, DT_IA_64_VMS_FIXUP_RELA_CNT)
        (DT_IA_64_VMS_FIXUP_NEEDED, DT_IA_64_VMS_SYMVEC_CNT)
        (DT_IA_64_VMS_XLATED, DT_IA_64_VMS_STACKSIZE)
        (DT_IA_64_VMS_UNWINDSZ, DT_IA_64_VMS_UNWIND_CODSEG)
        (DT_IA_64_VMS_UNWIND_INFOSEG, DT_IA_64_VMS_LINKTIME)
        (DT_IA_64_VMS_SEG_NO, DT_IA_64_VMS_SYMVEC_OFFSET)
        (DT_IA_64_VMS_SYMVEC_SEG, DT_IA_64_VMS_UNWIND_OFFSET)
        (DT_IA_64_VMS_UNWIND_SEG, DT_IA_64_VMS_STRTAB_OFFSET)
        (DT_IA_64_VMS_SYSVER_OFFSET, DT_IA_64_VMS_IMG_RELA_OFF)
        (DT_IA_64_VMS_SEG_RELA_OFF, DT_IA_64_VMS_FIXUP_RELA_OFF)
        (DT_IA_64_VMS_PLTGOT_OFFSET, DT_IA_64_VMS_PLTGOT_SEG)
        (DT_IA_64_VMS_FPMODE, SHN_IA_64_VMS_SYMVEC): Define

        * readelf.c (dump_relocations): Decode OpenVMS-specific sections.
        (get_ia64_dynamic_type): Decode OpenVMS-specific tags.
        (get_dynamic_type): Handle IA64-specific tags.
        (get_ia64_section_type_name): Handle OpenVMS-specific sections.
        (get_section_type_name): Handle OS-specific sections (and
        particularly IA64 OpenVMS one).
        (get_elf_section_flags): Makes flags static.  Add entries for IA64 and
        decode them.