[gold patch] Fix incremental update with comdat sections

[Cary Coutant <ccoutant at google dot com>]

During an incremental update, gold is failing to record the comdat
keys for kept comdat groups in unchanged files. This leads to an
internal error in a subsequent incremental update if a changed file
contains a copy of a comdat group that is still in the base file from
an unchanged file, and the group contains a non-weak definitions (such
as an STB_GNU_UNIQUE symbol).

The attached patch adds a test case and fixes the problem. OK to commit?

-cary


	* incremental.cc (Sized_relobj_incr::do_layout): Call
	report_comdat_group for kept comdat sections.
	* testsuite/Makefile.am (incremental_comdat_test_1): New test.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/incr_comdat_test_1.cc: New source file.
	* testsuite/incr_comdat_test_2_v1.cc: New source file.
	* testsuite/incr_comdat_test_2_v2.cc: New source file.
	* testsuite/incr_comdat_test_2_v3.cc: New source file.

Attachment: incr-comdat-patch.txt
Description: Text document