Tracepoint probes don't need extern C

tracepoint.h has the proper extern C guards, so every liblttng-ust API
called from the probe has the proper linkage.

The rest of the symbols are only meaningful within the probe, so we
don't care if they are mangled or not.

This fixes the two examples, and lttng-gen-tp.

Fixes #597

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
examples: tracepoint probes don't need extern C

Fix all UST demo applications under doc/examples/

Fixes #597

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Introduce configure --with-lttng-system-rundir

Allow overriding the path where the system-wide sessiond is expected to
keep its runtime files.

It does _not_ allow multiple instances of system-wide sessiond to run in
parallel though, because the wait shm files still requires having only
one single system-wide sessiond at any given time.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: liblttng_ust.la should depend on liblttng-ust-tracepoint.la

Changing -llttng-ust-tracepoint to liblttng-ust-tracepoint.la, so it
appears in the build dependencies.

Fixes #325

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fix: doc/examples cross-build

We need to pass automake's CPPFLAGS and LDFLAGS to examples. Add CFLAGS
too for completeness.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
tools/lttng-gen-tp: honor CPPFLAGS and LDFLAGS

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
doc/examples/gen-tp: pass automake CPPFLAGS/CFLAGS/LDFLAGS

Fix cross-build.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Merge branch 'master' of git://git.lttng.org/lttng-ust