Fix Squish4RunTestCase.sh to be POSIX compliant by exiting with 255
explicitly instead of depending on bash to translate -1 to 255. This
script is used by the SQUISH_V3_ADD_TEST and SQUISH_V4_ADD_TEST macros
provided by FindSquish.
This patch adds support for Squish 4.x.
The changes are basically what is attached to
http://public.kitware.com/Bug/view.php?id=9734.
When adding a test for squish 4.x, use squish_v4_add_test().
Alex