fix MSVC compilation errors

After commit 3701d499 'error_resilience: remove avpriv_atomic usage'
we have included windows.h in much more files and we should
avoid conflicts with defines/function declarations.

Signed-off-by: Mateusz Brzostek <mateuszb@poczta.onet.pl>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>