DLL-export is_valid_XXXnum() functions, for web server use

Fixes recently broken Win32 build
14 jobs for master in 9 minutes and 31 seconds (queued for 14 seconds)
Status Job ID Name Coverage
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passed #33716
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jsdoor-freebsd

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jsdoor-linux

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jsdoor-windows

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sbbs-freebsd

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sbbs-linux

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sbbs-windows

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sexpots-freebsd

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sexpots-linux

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sexpots-windows

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syncdraw-freebsd

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syncdraw-linux

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syncterm-freebsd

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syncterm-linux

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syncterm-windows

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