JIT

gh-134273: Allow setting JIT compiler flags with `CFLAGS_JIT` #3480

Job	Run time
Interpreter (Debug)	10m 16s
i686-pc-windows-msvc/msvc (Debug)	5m 17s
i686-pc-windows-msvc/msvc (Release)	4m 48s
x86_64-pc-windows-msvc/msvc (Debug)	4m 54s
x86_64-pc-windows-msvc/msvc (Release)	5m 11s
aarch64-pc-windows-msvc/msvc (Debug)	5m 43s
aarch64-pc-windows-msvc/msvc (Release)	5m 15s
x86_64-apple-darwin/clang (Debug)	8m 27s
x86_64-apple-darwin/clang (Release)	7m 9s
aarch64-apple-darwin/clang (Debug)	3m 43s
aarch64-apple-darwin/clang (Release)	2m 46s
x86_64-unknown-linux-gnu/gcc (Debug)	10m 58s
x86_64-unknown-linux-gnu/gcc (Release)	6m 49s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 34s
aarch64-unknown-linux-gnu/gcc (Release)	6m 16s
	1h 35m 6s

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