[binutils-gdb] Make __start/__stop symbols protected visibility

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 487b6440dad57440939fab7afdd84a218b612796 ***

Author: Alan Modra <amodra@gmail.com>
Branch: master
Commit: 487b6440dad57440939fab7afdd84a218b612796

Make __start/__stop symbols protected visibility

They can't be hidden visibility since apparently people use dlsym to
look them up.

bfd/
	PR ld/21964
	* elf-bfd.h (SYMBOLIC_BIND): Return TRUE for __start/__stop symbols.
	* elflink.c (bfd_elf_define_start_stop): Rewrite.
ld/
	PR ld/21964
	* testsuite/ld-elf/pr21562a.d: Update for changed start/stop symbols.
	* testsuite/ld-elf/pr21562b.d: Likewise.
	* testsuite/ld-elf/pr21562c.d: Likewise.
	* testsuite/ld-elf/pr21562d.d: Likewise.
	* testsuite/ld-elf/pr21562e.d: Likewise.
	* testsuite/ld-elf/pr21562f.d: Likewise.
	* testsuite/ld-elf/pr21562g.d: Likewise.
	* testsuite/ld-elf/pr21562h.d: Likewise.
	* testsuite/ld-elf/pr21562i.d: Likewise.
	* testsuite/ld-elf/pr21562j.d: Likewise.
	* testsuite/ld-elf/pr21562k.d: Likewise.
	* testsuite/ld-elf/pr21562l.d: Likewise.
	* testsuite/ld-elf/pr21562m.d: Likewise.
	* testsuite/ld-elf/pr21562n.d: Likewise.
	* testsuite/ld-elf/sizeofa.d: Likewise.
	* testsuite/ld-elf/sizeofb.d: Likewise.
	* testsuite/ld-elf/startofa.d: Likewise.
	* testsuite/ld-elf/startofb.d: Likewise.
	* testsuite/ld-gc/pr20022.d: Likewise.
	* testsuite/ld-gc/start.d: Likewise.
	* testsuite/ld-elf/pr21964-1a.c: New file.
	* testsuite/ld-elf/pr21964-1b.c: New file.
	* testsuite/ld-elf/pr21964-2a.c: New file.
	* testsuite/ld-elf/pr21964-2b.c: New file.
	* testsuite/ld-elf/shared.exp: Run PR ld/21964 tests.