feat(userspace): Add banned.h which includes banned functions.

This defines certain functions as invalid tokens, i.e., when
compiled, the compiler throws an error.

Currently only `strcpy` is included as a banned function.

Fixes #788

Signed-off-by: Vaibhav <vrongmeal@gmail.com>

userspace/engine/json_evt.cpp

@@ -21,6 +21,7 @@ limitations under the License.
 
 #include "falco_common.h"
 #include "json_evt.h"
+#include "banned.h"
 
 using json = nlohmann::json;
 using namespace std;