Skip an archive element if not added by linkerusers/hjl/pr20103

During archive rescan to resolve symbol references for files added by
LTO, linker add_archive_element callback is called to check if an
archive element should added.  After all IR symbols have been claimed,
linker won't claim new IR symbols and shouldn't add the LTO archive
element.  This patch updates linker add_archive_element callback to
return FALSE when seeing an LTO archive element during rescan and
changes ELF linker to skip such archive element.  Other linker backends
may also need similar update.

bfd/

	PR ld/20103
	* elflink.c (elf_link_add_archive_symbols): Skip archive element
	if linker add_archive_element callback returns FALSE.

ld/

	PR ld/20103
	* ldmain.c (add_archive_element): Don't claim new IR symbols
	after all IR symbols have been claimed.
	* plugin.c (plugin_call_claim_file): Remove no_more_claiming
	check.
	* testsuite/ld-plugin/lto.exp (pr20103): New proc.
	Run PR ld/20103 tests.
	* testsuite/ld-plugin/pr20103a.c: New file.
	* testsuite/ld-plugin/pr20103b.c: Likewise.
	* testsuite/ld-plugin/pr20103c.c: Likewise.

1 files changed, 3 insertions, 0 deletions

diff --git a/ld/testsuite/ld-plugin/pr20103b.c b/ld/testsuite/ld-plugin/pr20103b.c
new file mode 100644
index 00000000000..ead122dbe9b
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr20103b.c
@@ -0,0 +1,3 @@
+void dead()
+{
+}