layers: Fix 32-bit Windows build

layers: Fix 32-bit Windows build

A reinterpret_cast from a non-dispatch handle to uint64_t was failing on
windows 32-bit where non-dispatch handles are defined as 'typdef uint64_t
object'.  Changed reinterpret_cast to a C-style cast, as is consistent
with the rest of the non-dispatch handle to uint64_t conversions in
draw_state.