Feature patch: Shadowing m4 includes.

[Petter Urkedal]

The problem:  When a package is installed in two places, the macros
in the m4 files conflict.  This patch adds an option `--shadow'
which treats m4 files similarily as C include files, it only
includes the first file seen with a given name (sans dirname).

Thus, by adding the -I options in the correct order, i.e. the
same order as corresponding `$PATH's `$LD_LIBRARY_PATH's etc.,
it is possible to use aclocal on a system with a duplicate
installation of a package.

The patch also adds an options `--print-files' which causes
aclocal to print out which files it uses.

Cheers,
2001-01-19  Petter Urkedal  <address@hidden>

        * aclocal.in: New options `--shadow', `--print-files':
        ($opt_shadow, $opt_print_files, %filename_seen): New variables.
        (usage): Add doc.
        (parse_arguments): Add `--shadow' and `--print-files'.
        (scan_m4_files): Implement `--shadow'.
        (add_file): Implement `--print-files'.

automake-shadow.patch
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