bug#20416: message about ACLOCAL_AMFLAGS

[Vincent Lefevre]

With libtool 2.4.2 (but 2.4.6 seems to behave in the same way
according to the source), after removing a ACLOCAL_AMFLAGS line
in Makefile.am of some software, I get:

[...]
autoreconf: running: libtoolize --copy --force
libtoolize: putting auxiliary files in `.'.
libtoolize: copying file `./ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIR, `m4'.
libtoolize: copying file `m4/libtool.m4'
libtoolize: copying file `m4/ltoptions.m4'
libtoolize: copying file `m4/ltsugar.m4'
libtoolize: copying file `m4/ltversion.m4'
libtoolize: copying file `m4/lt~obsolete.m4'
libtoolize: Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
[...]

See the last line, about ACLOCAL_AMFLAGS.

However the Automake NEWS file says:

  - The ACLOCAL_AMFLAGS special make variable will be fully deprecated in
    Automake 2.0: it will raise warnings in the "obsolete" category (but
    still no hard error of course, for compatibilities with the many, many
    packages that still relies on that variable).  You are advised to
    start relying on the new Automake support for AC_CONFIG_MACRO_DIRS
    instead (which was introduced in Automake 1.13).

meaning that ACLOCAL_AMFLAGS should no longer be used and
AC_CONFIG_MACRO_DIRS should be used instead, which is currently done
and taken into account, as seen above.

-- 
Vincent Lefèvre <address@hidden> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)