gh-90300: Document equivalent -X options for envvars in the Python CL… #38

Job	Run time
i686-pc-windows-msvc/msvc (Debug)	18m 46s
i686-pc-windows-msvc/msvc (Release)	20m 51s
x86_64-pc-windows-msvc/msvc (Debug)	16m 17s
x86_64-pc-windows-msvc/msvc (Release)	20m 32s
aarch64-pc-windows-msvc/msvc (Debug)	5m 7s
aarch64-pc-windows-msvc/msvc (Release)	5m 48s
x86_64-apple-darwin/clang (Debug)	12m 14s
x86_64-apple-darwin/clang (Release)	16m 36s
aarch64-apple-darwin/clang (Debug)	9m 32s
aarch64-apple-darwin/clang (Release)	13m 19s
x86_64-unknown-linux-gnu/gcc (Debug)	8m 6s
x86_64-unknown-linux-gnu/gcc (Release)	17m 32s
x86_64-unknown-linux-gnu/clang (Debug)	7m 28s
x86_64-unknown-linux-gnu/clang (Release)	13m 48s
aarch64-unknown-linux-gnu/gcc (Debug)	56m 42s
aarch64-unknown-linux-gnu/gcc (Release)	46m 30s
aarch64-unknown-linux-gnu/clang (Debug)	53m 25s
aarch64-unknown-linux-gnu/clang (Release)	30m 26s
	6h 12m 59s

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