- not previously possible to configure a third-party gcc
with system gmp/mpfr/mpc.
This makes it easier to switch between compilers for testing.
- use system libraries by default
etc/config.sh and etc/config.csh
This structure is more convenient to add support for other shells, e.g. zsh, fish etc.
Resolves feature request to simplify support for other shells in
http://www.openfoam.org/mantisbt/view.php?id=1232