posix_spawn_file_actions_addopen: Work around Solaris 11 2011-11 bug. * m4/spawn_h.m4 (gl_SPAWN_H_DEFAULTS): Initialize REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN. * m4/posix_spawn.m4 (gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN): New macro. * lib/spawn.in.h (posix_spawn_file_actions_addopen): Test REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN, not REPLACE_POSIX_SPAWN. * lib/spawn_faction_addopen.c: Add workaround implementation if HAVE_WORKING_POSIX_SPAWN. * modules/spawn (Makefile): Substitute REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN. * modules/posix_spawn_file_actions_addopen (configure.ac): Invoke gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN. Test REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN, not REPLACE_POSIX_SPAWN. (Depends-on): Update conditions. * doc/posix-functions/posix_spawn_file_actions_addopen.texi: Mention the Solaris 11 bug.