[samples] Make saveSample.sh a little bit more generic

Prepare saving canadian samples by making the saveSample.sh script
a little bit more generic, using conditional code-paths (even if
there's currently a single code-path).

 # Compute x86_64-specific values

 CT_DoArchTupleValues() {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}"

 }