scripts: add option to strip all toolchain executables

To reduce filesizes of the toolchain and even improve build times
of projects to be build with this toolchain it is usefull to strip
the delivered toolchain executables. Since it is not likely that we
will debug the toolchain executables itself we do not need the
debug information inside the executables itself.

Signed-off-by: Remy Bohmer <linux@bohmer.net>

 # Compute s390-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

     if [ "${CT_ARCH_64}" = "y" ]; then

         CT_TARGET_ARCH="s390x"

     fi

 }