ZJIT: Drop capstone, use built-in disassemblers #248

Job	Run time
ruby-bench (--zjit-call-threshold=2, --warmup=1 --bench=1 --excludes=shipit, --enable-zjit=dev_no...	14m 53s
make (zjit-check, --enable-yjit=dev --enable-zjit, 1.85.0)	4m 54s
make (ruby, combo build test, --enable-yjit --enable-zjit)	3m 5s
make (check, --zjit-call-threshold=1, -T --zjit-call-threshold=1, --enable-zjit=dev)	16m 57s
make (check, --zjit-disable-hir-opt --zjit-call-threshold=1, -T --zjit-disable-hir-opt -T --zjit-...	12m 42s
ZJIT macOS result	3s
	52m 34s

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