Add AM_TESTS_ENVIRONMENT to build system
Add AM_TESTS_ENVIRONMENT to build system

These variables will be available from the shell during `make check`.
This way, we'll be able to get rid of having configure.ac manage the
.sh files for running the tests.

nicholasmalaya/grins,nicholasmalaya/grins,nicholasmalaya/grins,nicholasmalaya/grins