JIT

gh-134273: Allow setting JIT compiler flags with `CFLAGS_JIT` #3626

Job	Run time
Interpreter (Debug)	9m 45s
i686-pc-windows-msvc/msvc (Debug)	23m 24s
i686-pc-windows-msvc/msvc (Release)	14m 22s
x86_64-pc-windows-msvc/msvc (Debug)	23m 37s
x86_64-pc-windows-msvc/msvc (Release)	15m 37s
aarch64-pc-windows-msvc/msvc (Debug)	21m 44s
aarch64-pc-windows-msvc/msvc (Release)	18m 23s
x86_64-apple-darwin/clang (Debug)	15m 25s
x86_64-apple-darwin/clang (Release)	10m 39s
aarch64-apple-darwin/clang (Debug)	12m 7s
aarch64-apple-darwin/clang (Release)	9m 35s
x86_64-unknown-linux-gnu/gcc (Debug)	10m 25s
x86_64-unknown-linux-gnu/gcc (Release)	6m 28s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 44s
aarch64-unknown-linux-gnu/gcc (Release)	5m 42s
	3h 24m 57s

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