JIT

gh-134273: Allow setting JIT compiler flags with `CFLAGS_JIT` #3489

Job	Run time
Interpreter (Debug)	9m 55s
i686-pc-windows-msvc/msvc (Debug)	5m 25s
i686-pc-windows-msvc/msvc (Release)	5m 25s
x86_64-pc-windows-msvc/msvc (Debug)	5m 15s
x86_64-pc-windows-msvc/msvc (Release)	5m 12s
aarch64-pc-windows-msvc/msvc (Debug)	5m 22s
aarch64-pc-windows-msvc/msvc (Release)	5m 34s
x86_64-apple-darwin/clang (Debug)	7m 16s
x86_64-apple-darwin/clang (Release)	7m 49s
aarch64-apple-darwin/clang (Debug)	3m 32s
aarch64-apple-darwin/clang (Release)	2m 34s
x86_64-unknown-linux-gnu/gcc (Debug)	12m 0s
x86_64-unknown-linux-gnu/gcc (Release)	8m 46s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 39s
aarch64-unknown-linux-gnu/gcc (Release)	5m 45s
	1h 37m 29s

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