spurious unused function warning on static constructor/destructor

I don't think clang should emit an "unused function" warning when the function is declared as a constructor or a destructor (using Constructor/Destructor Attr).

Here is a patch that prevent warning and (used add two cases in the warn-unused-function.c test).

unused.patch (1.1 KB)

Makes sense, patch looks great, applied as r100870, thanks!