Adjust to recent changes to gnulib bootstrap.

Adjust to recent changes to gnulib bootstrap.

* .cvsignore, build-aux/.cvsignore, doc/.cvsignore, etc/.cvsignore:
* examples/calc++/.cvsignore, lib/.cvsignore, m4/.cvsignore:
* po/.cvsignore, runtime-po/.cvsignore, src/.cvsignore:
* tests/.cvsignore: Remove; I don't use CVS to maintain Bison
anymore and don't know of anybody else who does.  If someone needs
these files, they can resurrect them.
* .gitignore, build-aux/.gitignore, doc/.gitignore, lib/.gitignore:
* m4/.gitignore, po/.gitignore, runtime-po/.gitignore:
Omit leading '/', since bootstrap omits it.
Adjust file names to match current contents better.
* bootstrap: Sync from gnulib: this contains the new gnulib_mk_hook
installed just for us.
* bootstrap.conf (excluded_files): Don't exclude codeset.m4,
glibc21.m4, inttypes_h.m4, size_max.m4, xsize.m4, as they are now
needed somehow.  Don't have time to look into why.
(gnulib_modules): Change malloc to malloc-gnu.  Do we really assume
the GNU malloc behavior, where malloc (0) != NULL unless we're
out of storage?  If not, we can omit malloc-gnu; but for now I left
it in to be safe.
(vc_ignore): Remove.
(gnulib_mk_hook): New function.
* README-hacking: Renamed from HACKING, since gnulib bootstrap now
uses that convention.