Revert "win32: remove old attempts to define snprintf _snprintf"

This reverts commit 3bceb9cf.

include/vlc_common.h

@@ -783,6 +783,14 @@ VLC_EXPORT( char *, vlc_strcasestr, ( const char *s1, const char *s2 ) LIBVLC_US
 
 #   ifndef alloca
 #       define alloca _alloca
+#   endif
+
+    /* These two are not defined in mingw32 (bug?) */
+#   ifndef snprintf
+#       define snprintf _snprintf
+#   endif
+#   ifndef vsnprintf
+#       define vsnprintf _vsnprintf
 #   endif
 
 #   include <tchar.h>