tests: Move the common defines to a shared include file

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Fix make distcheck

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Makefile: Simplify the test compilation

Instead of setting CFLAGS and LDADD for each and every test, use a
pattern-based rule and per-target variables.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
message: The length in the header does not include itself

When assembling the length-prefixed protocol buffer, the length does not
contain its own length.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
riemann-client: Example client program

A very simple example program that writes the result to standard
output (for now), which can be sent away to Riemann with socat or
something similar.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>