JIT

GH-126910: reserve FP on AArch64 when generating JIT stencils #5711

Job	Run time
aarch64-unknown-linux-gnu/gcc (Release)	6m 42s
JIT without optimizations (Debug)	3m 39s
x86_64-apple-darwin/clang (Debug)	44m 26s
i686-pc-windows-msvc/msvc (Debug)	29m 38s
x86_64-unknown-linux-gnu/gcc (Release)	8m 10s
aarch64-unknown-linux-gnu/gcc (Debug)	8m 52s
JIT with tail calling interpreter	4m 45s
x86_64-apple-darwin/clang (Release)	32m 12s
aarch64-apple-darwin/clang (Debug)	12m 17s
x86_64-pc-windows-msvc/msvc (Release)	16m 36s
aarch64-apple-darwin/clang (Release)	13m 12s
x86_64-unknown-linux-gnu/gcc (Debug)	13m 47s
x86_64-pc-windows-msvc/msvc (Debug)	24m 50s
i686-pc-windows-msvc/msvc (Release)	15m 33s
aarch64-pc-windows-msvc/msvc (Release)	19m 10s
Interpreter (Debug)	12m 1s
aarch64-pc-windows-msvc/msvc (Debug)	28m 38s
Free-Threaded (Debug)	3m 44s
	4h 58m 12s

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