Apparently, some build environments require dxva.h even for dxva2,
while others lack this header entirely. Including it conditionally
allows building in both cases.
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit fa84506177f0246b30d4ea6a99ee5d419f3e4550)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>