JIT

gh-134273: Allow setting JIT compiler flags with `CFLAGS_JIT` #3575

Job	Run time
Interpreter (Debug)	9m 31s
i686-pc-windows-msvc/msvc (Debug)	22m 55s
i686-pc-windows-msvc/msvc (Release)	11m 55s
x86_64-pc-windows-msvc/msvc (Debug)	20m 27s
x86_64-pc-windows-msvc/msvc (Release)	11m 59s
aarch64-pc-windows-msvc/msvc (Debug)	20m 13s
aarch64-pc-windows-msvc/msvc (Release)	19m 46s
x86_64-apple-darwin/clang (Debug)	14m 48s
x86_64-apple-darwin/clang (Release)	11m 6s
aarch64-apple-darwin/clang (Debug)	11m 16s
aarch64-apple-darwin/clang (Release)	10m 22s
x86_64-unknown-linux-gnu/gcc (Debug)	10m 48s
x86_64-unknown-linux-gnu/gcc (Release)	6m 18s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 11s
aarch64-unknown-linux-gnu/gcc (Release)	5m 42s
	3h 14m 17s

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