[PATCH 0/5] speed up gnulib-tool some more

[Ralf Wildenhues]

This patch series is a repost and update of the unapplied parts of
<http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/16147>
plus a couple of new patches; prompted by
<http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/20351/focus=20370>.

The first two patches, taken together, have a net effect of 10-20%
speedup on normal gnulib-tool usage.  The third patch is a minor
peephole optimization.

Simon reported this to be very slow:
  gnulib-tool --test --with-tests

(or s/--test/--create-testdir/, that is fairly irrelevant)

Here, execution time is dominated by the license compatibility checking
code in func_create_testdir.  The fourth patch in this series speeds up
this check from something like 4.5 min to 26s on my system, but it also
changes the semantics of the test a bit; see the patch for discussion.

The last patch in this series fixes some of the fallout.

All in all, this series should cut well over half the gnulib-tool
running time for Simon.  It has been casually tested to work on

AIX 5.3         ksh
FreeBSD         sh
GNU/Linux       bash, dash, ksh, ksh93
HP-UX 11.23/PA  ksh
Solaris 10      ksh
Tru64 5.1       ksh

It exposes a segfault with (unmaintained) pdksh on GNU/Linux.  I don't
think we need to cater to this.  IRIX 6.5 sed has too many problems for
gnulib-tool both without and with this patch series, but using GNU sed
there seems to work fine.

I'm willing to rework the patches for suggested/required changes, and
I'd volunteer to maintain the code, if that helps.  Thanks.

The patches are posted with git format-patch, so it should be possible
to apply them all at once from a pipe to 'git am -3' (the commit message
ends after the '---').

Cheers,
Ralf