test-suite: apply cleanup pass

Remove all non-modifiable items (target tuple, gcc version, toolchain path...)
Makefile syntax ( use $(...) instead of ${...} )
Update doc
Space-damage cleanups

# Compute IA-64-specific values

CT_DoArchTupleValues() {

    # The architecture part of the tuple:

    CT_TARGET_ARCH="${CT_ARCH}"

}