lttng: Don't build trace headers when lttng is disabled

Signed-off-by: Adam Crume <adamcrume@gmail.com>
lttng: Remove -lboost_regex from unit test

Signed-off-by: Adam Crume <adamcrume@gmail.com>
lttng: Fix build error on 32-bit systems

Signed-off-by: Adam Crume <adamcrume@gmail.com>