LibC: Add stubs for some functions in {dlfcn,ftw,utime,wchar}.h

userspace/libraries/LibC/wchar.cpp

@@ -0,0 +1,8 @@
+#include <BAN/Assert.h>
+
+#include <wchar.h>
+
+size_t mbrtowc(wchar_t* __restrict, const char* __restrict, size_t, mbstate_t* __restrict)
+{
+	ASSERT_NOT_REACHED();
+}