libcamera: Add tracing to meson summary

The meson option summary currently does not report if the support
for tracing is enabled or not. Add it.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/meson.build

@@ -70,8 +70,11 @@ if libgnutls.found()
 endif
 
 if liblttng.found()
+    tracing_enabled = true
     config_h.set('HAVE_TRACING', 1)
     libcamera_sources += files(['tracepoints.cpp'])
+else
+    tracing_enabled = false
 endif
 
 if libudev.found()