selftests/bpf: Fix the invalid operand for instruction issue

The following issue occurs when compiling with clang version 17.0.6,
but not with version 18.1.8. Add a version restriction to fix this problem.

progs/compute_live_registers.c:251:3: error: invalid operand for instruction
  251 |                 "r0 = 1;"
      |                 ^
<inline asm>:1:22: note: instantiated into assembly here
    1 |         r0 = 1;r2 = 2;if r1 & 0x7 goto +1;exit;r0 = r2;exit;
      |                             ^
1 error generated.

Fixes: 4a4b84b ("selftests/bpf: verify jset handling in CFG computation")
Signed-off-by: Feng Yang <[email protected]>

Author: kknjh

tools/testing/selftests/bpf/progs/compute_live_registers.c

@@ -240,6 +240,7 @@ __naked void if2(void)
 		::: __clobber_all);
 }
 
+#if __clang_major__ >= 18
 /* Verifier misses that r2 is alive if jset is not handled properly */
 SEC("socket")
 __log_level(2)
@@ -255,6 +256,7 @@ __naked void if3_jset_bug(void)
 		"exit;"
 		::: __clobber_all);
 }
+#endif
 
 SEC("socket")
 __log_level(2)