tests: Move tap-driver.sh out of the autotools aux directory

We have made local modifications to this script, move it to the test
suite directory so it doesn't get overwritten by an updated version from
autotools.

Running 'make check' on current RHEL or Fedora without this patch
results in the following error:

  make[5]: Entering directory '/builddir/build/BUILD/lttng-tools-2.12.4/tests/regression'
  tap-driver.sh: invalid option: '--post-script'

Change-Id: I22823176cc5b98901865c9415250ce8e49384cbd
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>