There is a missing "else" in 'jobserver_info::jobserver_info' in "opts-common.cc".
As a result, if MAKEFLAGS is set and contains "--jobserver-auth=" and the jobserver auth string is not in one of the expected formats, then the message '"--jobserver-auth=' is not present in MAKEFLAGS" is printed. The message apparently intended in that case, "cannot access '--jobserver-auth=' file descriptors", can never be printed. Native Windows builds of GNU make put the name of a named semaphore in the auth string, as "--jobserver-auth=gmake_semaphore_22416". (This is "--jobserver-style=sem" and is the only available style in native Windows GNU Make, as of Make 4.4.) It would be nice to mention in the "-flto" documentation that this is not supported.
