Clang emits -Wdefault-const-init-var-unsafe when using u64_to_user_ptr()
due to the typecheck() macro creating an uninitialized dummy variable.
Replace u64_to_user_ptr() with an explicit cast through uintptr_t to
avoid the warning while keeping the same behavior.
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
28e63022dc