Switch to CMake built-in precompiled headers (resolve #657)

[tanaya-mankad]

Resolves #657. I believe my desktop builds now work the way you intended. This fix rewrites the PCH macro in modern CMake.

• Replace the manual MSVC-only /Yc + /Yu StdAfx.cpp scheme with CMake's built-in target_precompile_headers(), which is generator- and compiler-agnostic (Ninja, MSBuild, GCC/Clang).

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Background

The built-in support force-includes cnglob.h into every translation unit in addition to each source's own #include "cnglob.h". Because cnglob.h lacked an include guard, this double inclusion caused many redefinition errors. The old /Yu"cnglob.h" scheme masked this because MSVC discards all source text up to and including the #include "cnglob.h" line, so the header was only processed once.

Changes

• CMakeLists.txt: require CMake >= 3.16 for target_precompile_headers()
• src/CMakeLists.txt: drop the addMSVCPrecompiledHeader macro and StdAfx.cpp precomp entry; add target_precompile_headers(CSE PRIVATE "cnglob.h")
• src/cnglob.h: add an #ifndef GLOB include guard (the symbol the file's own comment already anticipated) to make the header idempotent
• src/stdafx.cpp: remove (no longer needed)

🤖 Generated with Claude Code

[chipbarnaby]

Works for the DEBUG<->RELEASE flip back and forth use case.

[nealkruis]

Also addresses #330.