Run pythoninfo-build on Emscripten

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Run pythoninfo-build to display the build information of the build Python.

Replace also "run --pythoninfo" with "pythoninfo-host" command.

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This PR requires python/cpython#152217 and python/cpython#152218 to be merged first.

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This PR requires python/cpython#152217 and python/cpython#152218 to be merged first.

Done, they have been merged.

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Ok. Let's see how it goes.

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It works as expected!

Build: https://buildbot.python.org/#/builders/1810/builds/2989

Display build info of the build Python:

sys.version: 3.16.0a0 (heads/main-dirty:7676427cd87, Jun 25 2026, 17:06:04) [GCC 12.2.0]
...
system.boot_id: 19de3398-fc70-4b07-8ce6-546009bdae58
system.machine_id: ec296ac077af2a1238433560f3a532c7
system.uptime: 498 days, 2:48:15

Display build info of the host/Emscripten Python:

sys.version: 3.16.0a0 (heads/main-dirty:7676427cd87, Jun 25 2026, 16:32:37) [Clang 23.0.0git (https:/github.com/llvm/llvm-project c6c2ad52586c28e74a72457098
...
system.machine_id: ec296ac077af2a1238433560f3a532c7