Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

vendor/bitflags/src/external/bytemuck.rs

@@ -0,0 +1,19 @@
+#[cfg(test)]
+mod tests {
+    use bytemuck::{Pod, Zeroable};
+
+    bitflags! {
+        #[derive(Pod, Zeroable, Clone, Copy)]
+        #[repr(transparent)]
+        struct Color: u32 {
+            const RED = 0x1;
+            const GREEN = 0x2;
+            const BLUE = 0x4;
+        }
+    }
+
+    #[test]
+    fn test_bytemuck() {
+        assert_eq!(0x1, bytemuck::cast::<Color, u32>(Color::RED));
+    }
+}