std.stdio: Fix generating documentation on POSIX

Declare a dummy HANDLE alias to allow the compilation of the
Windows-only File methods.
Fix issue 8580 - Peek returns an invalid pointer for structs larger than Variant.size.

Style: Add space between if and condition.
Merge pull request #1948 from CyberShadow/std-stdio-handle-doc

std.stdio: Fix generating documentation on POSIX
Fix broken master due to dangling else block.
Merge pull request #1949 from AndrejMitrovic/FixBuild

Fix broken master due to dangling else block.
Merge pull request #1934 from Kapps/fix8580

Fix issue 8580 - Peek returns an invalid pointer for structs larger than Variant.size.