Extend .symver directive to update visibility of the original symbol and
assign one original symbol to different versioned symbols:
.symver foo, foo@VERS_1, local # Change foo to a local symbol.
.symver foo, foo@VERS_2, hidden # Change foo to a hidden symbol.
.symver foo, foo@@VERS_3, remove # Remove foo from symbol table.
.symver foo, bar@V1 # Assign foo to bar@V1 and baz@V2.
.symver foo, baz@V2
PR gas/23840
PR gas/25295
* NEWS: Mention .symver extension.
* config/obj-elf.c (obj_elf_find_and_add_versioned_name): New
function.
(obj_elf_symver): Call obj_elf_find_and_add_versioned_name to
add a version name. Add local, hidden and remove visibility
support.
(elf_frob_symbol): Handle the list of version names. Update the
original symbol to local, hidden or remove it from the symbol
table.
(elf_frob_file_before_adjust): Handle the list of version names.
* config/obj-elf.h (elf_visibility): New.
(elf_versioned_name_list): Likewise.
(elf_obj_sy): Change local to bitfield. Add rename, bad_version
and visibility. Change versioned_name pointer to struct
elf_versioned_name_list.
* doc/as.texi: Update .symver directive.
* testsuite/gas/symver/symver.exp: Run all *.d tests. Add more
error checking tests.
* testsuite/gas/symver/symver6.d: New file.
* testsuite/gas/symver/symver7.d: Likewise.
* testsuite/gas/symver/symver7.s: Likewise.
* testsuite/gas/symver/symver8.d: Likewise.
* testsuite/gas/symver/symver8.s: Likewise.
* testsuite/gas/symver/symver9.s: Likewise.
* testsuite/gas/symver/symver9a.d: Likewise.
* testsuite/gas/symver/symver9b.d: Likewise.
* testsuite/gas/symver/symver10.s: Likewise.
* testsuite/gas/symver/symver10a.d: Likewise.
* testsuite/gas/symver/symver10b.d: Likewise.
* testsuite/gas/symver/symver11.d: Likewise.
* testsuite/gas/symver/symver11.s: Likewise.
* testsuite/gas/symver/symver12.d: Likewise.
* testsuite/gas/symver/symver12.s: Likewise.
* testsuite/gas/symver/symver13.d: Likewise.
* testsuite/gas/symver/symver13.s: Likewise.
* testsuite/gas/symver/symver14.d: Likewise.
* testsuite/gas/symver/symver14.l: Likewise.
* testsuite/gas/symver/symver15.d: Likewise.
* testsuite/gas/symver/symver15.l: Likewise.
* testsuite/gas/symver/symver6.l: Removed.
* testsuite/gas/symver/symver6.s: Updated.
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