Statically link libtimecode into libmidi++ instead of libardour

This is necessary to get the libmidi++ test to work as libmidi++ has
unresolved symbols in libtimecode. This was not a problem when libtimecode
was statically linked into libardour if the executable depended on both
libtimecode and libardour as the symbols would get resolved.

This is not true for the midi++ test case as it doesn't depend on libardour

Also as libmidi++ only references symbols from one object file in the
libtimecode static archive only that object file gets included/exported
from libmidi++.

This is fixed by adding a dummy reference to a symbol in the other object
file in the libtimecode static archive.