[CGP] cond ? x / y: x / C should generate branch instead of cmov

https://godbolt.org/z/zsh7YG3c3
```c
#include

int foo(int x, int y, bool k){
return k ? x / y: x / 7;
}
```
clang:
```asm
foo:
mov eax, edi
test edx, edx
mov ecx, 7
cmovne ecx, esi
cdq
idiv ecx
ret
```
gcc:
```asm
"foo":
test dl, dl
mov eax, edi
je .L2
cdq
idiv esi
ret
.L2:
movsxd rdx, edi
sar eax, 31
imul rdx, rdx, -1840700269
shr rdx, 32
add edx, edi
sar edx, 2
sub eax, edx, eax
ret
```

clang missed optimization opportunity of division by a constant. Since division has high latency, the branch cost may not be high.