build-aux: ensure all scripts are included in EXTRA_DIST

build-aux: ensure all scripts are included in EXTRA_DIST

Few of the scripts in build-aux are included in EXTRA_DIST. This is not
a serious problem since they are primarily tools intended for developers
upstream, and downstream builds won't need them. Having them missing,
however, complicates downstream patching because it means patches that
are auto-exported from git will fail to apply if they include a change
to a file in build-aux/.  By bundling all these scripts in the dist we
make patching more straightforward.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>