From the gnulib ChangeLog ...
m4/dos.m4 needs to go. It laboriously invokes the C compiler, and
extracts symbols from it, puts them into config.h; but it's much
easier to use the symbols directly. filename.h already does this,
but it disagrees with dos.m4 in some respects. This patch
introduces a different include file dosname.h that packages up
dos.m4, and then later we can work on merging filename.h and
dosname.h. Applications that need only the easy-to-configure
symbols should consider including dosname.h rather than dirname.h.
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After a maintainer clean, the build process not terminates with ...
./bootstrap: aclocal --force -I m4 -I/sw/share/aclocal ...
aclocal: aclocal: file `m4/dos.m4' does not exist
Ben