JIT

GH-126910: reserve FP on AArch64 when generating JIT stencils (GH-146… #5722

Job	Run time
Interpreter (Debug)	12m 39s
JIT without optimizations (Debug)	3m 36s
x86_64-pc-windows-msvc/msvc (Release)	15m 8s
aarch64-apple-darwin/clang (Debug)	13m 11s
x86_64-unknown-linux-gnu/gcc (Release)	8m 53s
x86_64-unknown-linux-gnu/gcc (Debug)	13m 55s
aarch64-apple-darwin/clang (Release)	13m 36s
i686-pc-windows-msvc/msvc (Debug)	29m 19s
x86_64-apple-darwin/clang (Release)	34m 40s
aarch64-unknown-linux-gnu/gcc (Debug)	8m 45s
i686-pc-windows-msvc/msvc (Release)	15m 0s
x86_64-apple-darwin/clang (Debug)	38m 16s
aarch64-unknown-linux-gnu/gcc (Release)	7m 15s
aarch64-pc-windows-msvc/msvc (Debug)	24m 25s
aarch64-pc-windows-msvc/msvc (Release)	22m 0s
Free-Threaded (Debug)	3m 39s
x86_64-pc-windows-msvc/msvc (Debug)	30m 7s
JIT with tail calling interpreter	4m 2s
	4h 58m 26s

Provide feedback