[native_toolchain_c] Support environment for `cl.exe` already set up #1139

Job	Run time
build (ubuntu, stable, native_assets_builder, false)	5m 11s
build (ubuntu, stable, native_assets_cli, false)	2m 10s
build (ubuntu, stable, native_toolchain_c, false)	2m 3s
build (ubuntu, dev, native_assets_builder, false)	5m 26s
build (ubuntu, dev, native_assets_cli, false)	2m 25s
build (ubuntu, dev, native_toolchain_c, false)	2m 26s
build (macos, stable, native_assets_builder, false)	6m 38s
build (macos, stable, native_assets_cli, false)	1m 9s
build (macos, stable, native_toolchain_c, false)	2m 15s
build (macos, dev, native_assets_builder, false)	4m 14s
build (macos, dev, native_assets_cli, false)	1m 23s
build (macos, dev, native_toolchain_c, false)	1m 33s
build (windows, stable, native_assets_builder, false)	7m 30s
build (windows, stable, native_assets_cli, false)	4m 1s
build (windows, stable, native_toolchain_c, false)	3m 38s
build (windows, dev, native_assets_builder, false)	8m 55s
build (windows, dev, native_assets_cli, false)	3m 9s
build (windows, dev, native_toolchain_c, false)	5m 26s
coverage-finished	5s
	1h 9m 37s

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