bug#67539: GNU Automake 1.16.5 FAILS one test objc-megademo

[Karl Berry]

    partially related to how Automake is calling libtool from the 
    build rules (it is missing the --tag option), 

I added the tags to automake as previously posted here.
(https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67539)

    no tag defined for Objective C[1] (presumably it would be --tag=OBJC)
    ...
    "If [libtool] can't infer a tag, then it defaults to the
    configuration for the C language"
    ...
    lobby for the manual to change rather than rollback the behavior.

I wrote bug-libtool about these things.
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67754

Thanks,
Karl