selftests/bpf: Add selftest for may_goto

selftests/bpf: Add selftest for may_goto

Added test cases to ensure that programs with stack sizes exceeding 512
bytes are restricted in non-JITed mode, and can be executed normally in
JITed mode, even with stack sizes exceeding 512 bytes due to the presence
of may_goto instructions.

Test result:
echo "0" > /proc/sys/net/core/bpf_jit_enable
./test_progs -t verifier_stack_ptr
...
stack size 512 with may_goto with jit:SKIP
stack size 512 with may_goto without jit:OK
...
Summary: 1/27 PASSED, 25 SKIPPED, 0 FAILED

echo "1" > /proc/sys/net/core/bpf_jit_enable
./test_progs -t verifier_stack_ptr
...
stack size 512 with may_goto with jit:OK
stack size 512 with may_goto without jit:SKIP
...
Summary: 1/27 PASSED, 25 SKIPPED, 0 FAILED

Signed-off-by: Jiayuan Chen <mrpre@163.com>
Link: https://lore.kernel.org/r/20250214091823.46042-4-mrpre@163.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>