Remove redondant "hello" test and move "hello-static-lib" to doc/examples

The examples are now automatically built as part of the default make target.

The "hello" test verified that an application with statically embedded
tracepoint providers could be built. This is now covered by "easy-ust" in
doc/examples since we now build the examples.

Move the "hello-static-lib" test to doc/examples.

This should provide complete and easy to understand Makefile examples to users
who wish to integrate tracepoint providers to their applications.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>