CORE-12686
This collection of libraries consist in:
- a down-level `pathcch_static` PathCch library, to be used for programs
that need to run on Windows 7 and below;
- Windows 8+ compatible libraries importing from either kernelbase.dll
(`pathcch_kernelbase`), or from the corresponding APISET
api-ms-win-core-path-l1-1-0.dll (`pathcch`, which is Win8+ PSDK
compatible).
The down-level static library is compiled by reusing the newly-introduced
kernelbase's path.c, instead of using a specific pathcch.c.
Unrelated functions are excluded from compilation by putting them into
`#ifndef STATIC_PATHCCH ..... #endif` blocks.
Hermès Bélusca-Maïto