JIT

Support LLVM_VERSION configuration via env #12

Job	Run time
Interpreter (Debug)	9m 40s
x86_64-pc-windows-msvc/msvc (Debug)	23m 55s
i686-pc-windows-msvc/msvc (Release)	15m 45s
aarch64-pc-windows-msvc/msvc (Debug)	27m 24s
x86_64-apple-darwin/clang (Release)	19m 11s
x86_64-pc-windows-msvc/msvc (Release)	14m 46s
aarch64-pc-windows-msvc/msvc (Release)	20m 37s
i686-pc-windows-msvc/msvc (Debug)	23m 38s
aarch64-apple-darwin/clang (Debug)	10m 12s
aarch64-unknown-linux-gnu/gcc (Release)	5m 47s
x86_64-apple-darwin/clang (Debug)	18m 25s
aarch64-apple-darwin/clang (Release)	10m 5s
x86_64-unknown-linux-gnu/gcc (Debug)	10m 42s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 33s
x86_64-unknown-linux-gnu/gcc (Release)	8m 14s
	3h 45m 54s

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