fix(userspace/engine): guard lua state into falco engine

Co-authored-by: Lorenzo Fontana <lo@linux.com>
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>

userspace/engine/falco_common.h

@@ -21,6 +21,7 @@ limitations under the License.
 
 #include <string>
 #include <exception>
+#include <mutex>
 
 extern "C" {
 #include "lua.h"
@@ -94,11 +95,10 @@ public:
 protected:
 	lua_State *m_ls;
 
+	std::mutex m_ls_semaphore;
+
 	sinsp *m_inspector;
 
 private:
 	void add_lua_path(std::string &path);
-};
-
-
-
+};