[Bug 38337] clang compiling warnings

https://bugs.winehq.org/show_bug.cgi?id=38337

--- Comment #20 from Sergey Isakov  ---
/Volumes/MacHD/Users/sergey/Documents/Projects/winehq/dlls/winemac.drv/cocoa_clipboard.m:163:45:
warning: null passed to a callee that requires a non-null argument [-Wnonnull]
                    ret = [NSBitmapImageRep
representationOfImageRepsInArray:reps
                                            ^
1 warning generated.
---------------------------------

/Volumes/MacHD/Users/sergey/Documents/Projects/winehq/dlls/winemac.drv/cocoa_window.m:1770:19:
warning: null passed to a callee that requires a non-null argument [-Wnonnull]
            [self windowDidResize:nil];
                  ^               ~~~
/Volumes/MacHD/Users/sergey/Documents/Projects/winehq/dlls/winemac.drv/cocoa_window.m:1949:27:
warning: null passed to a callee that requires a non-null argument [-Wnonnull]
                    [self windowDidResize:nil];
                          ^               ~~~
/Volumes/MacHD/Users/sergey/Documents/Projects/winehq/dlls/winemac.drv/cocoa_window.m:2848:15:
warning: null passed to a callee that requires a non-null argument [-Wnonnull]
        [self windowDidResize:nil];
              ^               ~~~
/Volumes/MacHD/Users/sergey/Documents/Projects/winehq/dlls/winemac.drv/cocoa_window.m:2864:15:
warning: null passed to a callee that requires a non-null argument [-Wnonnull]
        [self windowDidResize:nil];
              ^               ~~~
4 warnings generated.
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I don't know the logic