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>

 # Default test suite configuration

 # GCC configuration

 DG_GCC_VERSION = 4.3.2

 DG_GCC_URL = ftp://gcc.gnu.org/pub/gcc/releases/gcc-${DG_GCC_VERSION}/gcc-testsuite-${DG_GCC_VERSION}.tar.gz

 # Default DejaGnu configuration

 DG_TOOLNAME = gcc

 DG_TARGET_HOSTNAME = 127.0.0.1

 DG_TARGET_USERNAME = root

 DG_TARGET = powerpc-unknown-linux-gnu

 DG_SRC_DIR = ${TOPDIR}/gcc-${DG_GCC_VERSION}/gcc/testsuite

 DG_TOOLCHAIN_DIR = ${TOPDIR}/../../bin

 # Default tests

 DG_C_TESTS = 

 DG_CPP_TESTS =