[llvm] [BPF] Report warning for some insn imm requiring valid range in inline asm (PR #142989)

[via llvm-commits]

eddyz87 wrote:

Latest changes lgtm.
However, on a second thought, maybe `Imm < INT_MIN || Imm > UINT_MAX` makes more sense in the end.
E.g. corresponding selftest change is an unnecessary obfuscation:

```
--- a/tools/testing/selftests/bpf/progs/verifier_and.c
+++ b/tools/testing/selftests/bpf/progs/verifier_and.c
@@ -99,7 +99,7 @@ __naked void known_subreg_with_unknown_reg(void)
 	call %[bpf_get_prandom_u32];			\
 	r0 <<= 32;					\
 	r0 += 1;					\
-	r0 &= 0xFFFF1234;				\
+	r0 &= -60876;					\
```

https://github.com/llvm/llvm-project/pull/142989