Automatically make test-* targets; different script working dir.
Automatically make test-* targets; different script working dir.

Test script working directory changed to CMAKE_CURRENT_BINARY_DIR
for consistency with the rest of the test infrastructure.

add_test_label(NAME labels...) will automatically create test-LABEL
targets for each LABEL in labels...

add_test_class will not try and create a test-* target if the
target already exists.

biddisco/CMake,shurikasa/CMake,ptoharia/CMake,jafyvilla/CMake,ptoharia/CMake,jafyvilla/CMake,shuaibarshad/KAUST-CMake,shuaibarshad/KAUST-CMake,ptoharia/CMake,jafyvilla/CMake,jafyvilla/CMake,biddisco/CMake,biddisco/CMake,shurikasa/CMake,shurikasa/CMake,shuaibarshad/KAUST-CMake,shurikasa/CMake,shuaibarshad/KAUST-CMake,ptoharia/CMake,biddisco/CMake