configure: add CONFIG_DATE, GIT_CONFIG_SHA variables

Improve detecting common build errors (1)
make: pass build date and HEAD SHA during build via CFLAGS

Improve detecting common build errors (2)
rtapi/msgd: startup log with build+config dates and SHA's, warn on conflict

Improve detecting common build errors (3), and ease detecting
for logfile readers
tests/module-loading/shared-test.sh:  fix output error

fixup for e43c980 and #89

Error output doesn't match test that triggers the error.
Merge pull request #146 from zultron/mk-pull

tests/module-loading/shared-test.sh:  fix output error
Merge pull request #142 from mhaberler/make-clean-check

improve detecting common build errors when changing branches
scripts/check-system-configuration.sh:  suppress error

Don't print errors if /etc/security/....conf doesn't exist
Merge pull request #147 from zultron/master

scripts/check-system-configuration.sh:  suppress error
hal/python: Cython bindings for HAL by Pavel Shramov

see http://psha.org.ru/cgit/psha/emc2.git/commit/?h=wip-cython&id=7137c5f8874948541de1aa796c9e8c1b2f8f7fb8
License: MIT

my autoconf integration is naive and needs work - this should not depend on cython
and it should retrigger cython only if a pxy/pyx file changed
A regression test would be great.

To extend this work, you need cython installed:

  sudo apt-get install cython

Signed-off-by: Michael Haberler <git@mah.priv.at>
hal/cython: update Submakefile