if statement doesn't raise division-by-zero when divisor is passed from lambda

[Josh Barth]

# Steps to Reproduce
1. In sbcl run (funcall (lambda (x) (if (/ 3 x) t)) 0)

# Results
Evaluates to T. Doesn't raise any error.

# Expected Results
Should raise a division-by-zero error. The following statements all work as expected:

(funcall (lambda () (if (/ 3 0) t)))
(funcall (lambda (x) (if (eql (/ 3 x) 3) t)) 0)
(let ((x 0)) (if (/ 3 x) t))

# System

`sbcl --version`: SBCL 2.1.2.nixos
`uname -a`: Linux krypton 5.12.17 #1-NixOS SMP Wed Jul 14 15:00:33 UTC 2021 x86_64 GNU/Linux

(and, yes, I know, (if (/ 3 x)) makes no sense. this was a bit of a rabbit hole. regardless, i still think it's a bug)

[Stas Boukarev (stassats)]

It's flushed in non-safe code. Add (declare (optimize (safety 3))) if you want it to stay.