JIT

gh-134273: Allow setting JIT compiler flags with `CFLAGS_JIT` #3654

Job	Run time
Interpreter (Debug)	9m 51s
i686-pc-windows-msvc/msvc (Release)	11m 3s
i686-pc-windows-msvc/msvc (Debug)	20m 46s
aarch64-pc-windows-msvc/msvc (Debug)	21m 59s
x86_64-pc-windows-msvc/msvc (Release)	11m 33s
aarch64-apple-darwin/clang (Debug)	10m 49s
x86_64-apple-darwin/clang (Debug)	28m 58s
x86_64-pc-windows-msvc/msvc (Debug)	20m 25s
aarch64-apple-darwin/clang (Release)	10m 8s
x86_64-unknown-linux-gnu/gcc (Debug)	12m 2s
x86_64-unknown-linux-gnu/gcc (Release)	6m 31s
aarch64-unknown-linux-gnu/gcc (Release)	7m 16s
aarch64-unknown-linux-gnu/gcc (Debug)	6m 54s
aarch64-pc-windows-msvc/msvc (Release)	18m 0s
x86_64-apple-darwin/clang (Release)	15m 2s
	3h 31m 17s

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