JIT

[3.14] GH-134273: Allow setting JIT compiler flags at build time with… #3778

Job	Run time
Interpreter (Debug)	9m 40s
x86_64-pc-windows-msvc/msvc (Debug)	23m 21s
i686-pc-windows-msvc/msvc (Release)	13m 59s
i686-pc-windows-msvc/msvc (Debug)	20m 52s
aarch64-pc-windows-msvc/msvc (Release)	17m 32s
x86_64-apple-darwin/clang (Release)	11m 50s
x86_64-pc-windows-msvc/msvc (Release)	14m 50s
aarch64-pc-windows-msvc/msvc (Debug)	22m 44s
x86_64-unknown-linux-gnu/gcc (Debug)	10m 54s
aarch64-apple-darwin/clang (Release)	9m 10s
x86_64-apple-darwin/clang (Debug)	12m 47s
aarch64-apple-darwin/clang (Debug)	11m 29s
aarch64-unknown-linux-gnu/gcc (Release)	6m 28s
x86_64-unknown-linux-gnu/gcc (Release)	6m 25s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 45s
	3h 19m 46s

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