vlc_atomic: set the atomic types to be at least 32 bits wide with MSVC.
vlc_atomic: set the atomic types to be at least 32 bits wide with MSVC.

This change is required since some atomic operations of the
Interlocked API are only available for desktop apps.

Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,krichter722/vlc,shyamalschandra/vlc,krichter722/vlc,shyamalschandra/vlc,krichter722/vlc,xkfz007/vlc,shyamalschandra/vlc,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,vlc-mirror/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,xkfz007/vlc,krichter722/vlc,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,xkfz007/vlc,vlc-mirror/vlc,vlc-mirror/vlc,krichter722/vlc,xkfz007/vlc