The Windows build never actually used ccache; the '.ccache' directory
only ever held the win_flex_bison install, and cmake/MSVC did no compiler
caching. Clean this up:
- Drop the CCACHE_* environment variables from the job (meaningless here).
- Store win_flex_bison in a dedicated 'win_flex_bison' directory instead of
the misleadingly named '.ccache', and cache just that (static key, as it
is a fixed third-party tool).
- Set WIN_FLEX_BISON inside ci-win-compile.ps1 as an absolute path, rather
than in the workflow, making the script self-contained.
- Use the runner's processor count for build parallelism instead of a fixed
'-j 3', in both ci-win-compile.ps1 and ci-win-test.ps1.
- Remove the verilator-win.zip archive and upload steps; nothing consumes
that artifact.
- Build Verilator with the Ninja generator from an MSVC developer shell
instead of MSBuild. MSBuild only parallelizes across projects, and
Verilator is a single project, so it compiled serially; Ninja keeps all
cores busy. Also compile with /Od: this job only checks that Verilator
builds and can verilate an example, so an optimized binary is not needed
and the otherwise-dominant optimizer time is wasted.
cbd78e689c