Introduce builtin to get percpu kernel data #6

Job	Run time
build_test (LLVM 13, Debug, .#bpftrace-llvm13, biosnoop.bt)	16m 47s
build_test (LLVM 14, Debug, .#bpftrace-llvm14, biosnoop.bt)	16m 49s
clang-format	4m 2s
build_test (LLVM 15, Debug, .#bpftrace-llvm15, biosnoop.bt)	16m 50s
build_test (LLVM 16, Debug, .#bpftrace-llvm16, biosnoop.bt)	16m 48s
build_test (LLVM 17, Debug, .#bpftrace-llvm17, biosnoop.bt)	16m 52s
build_test (LLVM 18 Release, Release, .#bpftrace-llvm18, biosnoop.bt)	16m 28s
build_test (LLVM 18 Debug, Debug, .#bpftrace-llvm18, biosnoop.bt)	17m 10s
build_test (LLVM 18 Clang Debug, Debug, .#bpftrace-llvm18, clang, clang++, biosnoop.bt)	16m 6s
build_test (AOT (LLVM 18 Debug), Debug, .#bpftrace-llvm18, 0, 1, .github/include/aot_skip.txt)	10m 24s
build_test (Memleak test (LLVM 18 Debug), Debug, .#bpftrace-llvm18, 1, 0)	7m 52s
build_test (Memleak test (LLVM 18 Release), Release, .#bpftrace-llvm18, 1, 0)	9m 39s
irc	0s
	2h 45m 47s

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