Bitmap: short circuit on 0-byte clears

luna/src/Bitmap.cpp

@@ -62,6 +62,8 @@ void Bitmap::clear_region(usize start, usize bits, bool value)
     expect(initialized(), "Bitmap was never initialized");
     expect((start + bits) <= size(), "Bitmap clear out of range");
 
+    if (!bits) return;
+
     // Set individual bits while not on a byte boundary.
     while ((start % 8) && bits--)
     {