kept comdat section was garbage collected. * testsuite/Makefile.am: Add test gc_comdat_test.sh. * testsuite/Makefile.in: Regenerate. * testsuite/gc_comdat_test.sh: New file. * testsuite/gc_comdat_test_1.cc: New file. * testsuite/gc_comdat_test_2.cc: New file.