test-suite: Added new test suite feature (experimental)

This patch adds support for installing the gcc test suite. A helper
Makefile is provided for building and running the gcc tests.

The default configuration runs all gcc tests and requires automatic
ssh/scp login access to a networked target board. See README for
more details.

Note: Current feature is tested with the powerpc-unknown-linux-gnu
sample but it should work with others as well.

Signed-off-by: Martin Lund <mgl@doredevelopment.dk>

# Compute Alpha-specific values

CT_DoArchTupleValues () {

    # The architecture part of the tuple:

    CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_ALPHA_VARIANT}"

}