add ARPACK to the Octave sources?

[John W. Eaton]

The following bug report

  https://savannah.gnu.org/bugs/?31479

is about an issue that has been around for a long time with no
resolution.  The bug appears to actually be in ARPACK and we have a
fix for the problem.

Generally, I would prefer to fix problems like this in the upstream
sources and not include workarounds directly in Octave.
Unfortunately, ARPACK is not actively maintained by the original
authors (or anyone else as far as I know), and getting everyone who
packages ARPACK to fix this bug for us is probably not going to happen
either.  So I'm proposing that we fix the problem for Octave by
including ARPACK directly in the Octave sources along with our fixes,
the same as we do with some other numerical routines like lsode,
dassl, daspk, etc.

I have a series of patches ready to commit that will

    * add ARPACK to libcruft

    * remove configure checks and macros for ARPACK from the build
      system, add a note to the build system, fix install.txi, etc.

    * fix a declaration problem with ETIME in an ARPACK function

    * apply David's patch

    * fix an uninitialized memory problem I discovered with valgrind
      while doing some testing

Does anyone object to making these changes before 3.4?

If not, then I will check these changes in.

jwe