bug#54020: Impossible to pass `-no-suppress` to `libtool` via automake files

[Karl Berry]

Hi Damian - thanks for the report.

    LTCOMPILE = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
            $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) \
            $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) \
            $(AM_CFLAGS) $(CFLAGS)
    ...
    `libtool` has a command line option, `-no-suppress` ...

Well, the immediate answer would apparently be to add yet another
variable after the --mode=compile, say LTMODEOPTS for the sake of
argument (have to think about the name), so the output is

LTCOMPILE = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
        $(LIBTOOLFLAGS) --mode=compile $(LTMODEOPTS) $(CC) ...

Mike, Jim, wdyt? --thanks, karl.