Build directory option for configure script

[Daniel J Sebald]

Hello Autoconf,

The Octave maintainers had a discussion about adding an option to 
"configure" for a build directory.  The reason is that a lot of people 
like running configure from a directory other than the source tree so 
that 1) object files end up in a different directory that can easily be 
recursively removed to start over, and 2) multiple configurations and 
builds can be done (the analogy being a debug and non-debug menu 
selection in some C/C++ developer suite).

It was suggested this might be a generic feature rather than an 
Octave-added option.  So please give me your thoughts on adding this 
option to Autoconf.  By having this as an option, it lets people know 
that a separate build directory can be done, and it might be useful down 
the road to someone who wants to build a generic script.  Patterning 
after this:

Fine tuning of the installation directories:
  --bindir=DIR            user executables [EPREFIX/bin]
  --sbindir=DIR           system admin executables [EPREFIX/sbin]

it might be something like:

--builddir=DIR           object and libraries

which is essentially the same as doing:

mkdir ../DIR
cd ../DIR
../<projname>/configure OTHER_OPTS
cd ../<projname>

Or something like that.

Thanks,

Dan