lttng-modules: add dependency on kernel tracing

Fixes: #888

Signed-off-by: Nicolas Thill <nico@openwrt.org>

devel/lttng-modules/Makefile

@@ -26,7 +26,7 @@ define KernelPackage/lttng
   SUBMENU:=Other modules
   TITLE:=Linux Trace Toolkit: next generation (kernel modules)
   URL:=https://lttng.org/
-  DEPENDS:= @!TARGET_uml
+  DEPENDS:= @!TARGET_uml @KERNEL_FTRACE
   FILES:= \
 	$(PKG_BUILD_DIR)/lttng-*.$(LINUX_KMOD_SUFFIX) \
 	$(PKG_BUILD_DIR)/lib/lttng-*.$(LINUX_KMOD_SUFFIX) \