Fix compilation with windows.h from latest w32api
misc.h has complex logic (checking MAXSHORT is undefined etc.) controlling if it includes assert.h or not.
Including windows.h from w32api 9.0.0 before misc.h now trips over that, causing assert.h to not be included, causing various errors, e.g.
In file included from ../include/cursor.h:53, from ../include/dix.h:54, from ../os/osdep.h:139, from ../hw/xwin/winauth.c:40: ../include/privates.h: In function ‘dixGetPrivateAddr’: ../include/privates.h:121:5: error: implicit declaration of function ‘assert’ [-Werror=implicit-function-declaration]
Fix this by IWYU in privates.h