[CPP] Int/Int32 inconsistent results for shift left operations

Using left shift operation give different results when the static analyser is on or off
For example: ( https://try.haxe.org/#BAA31234)
```haxe
var x:Int = 1<<32;
trace("Int(x): " + x);
var n:Int = 1;
var m:Int = n << 32;
trace("Int(m): " + m);
var x:Int32 = 1<<32;
trace("Int32(x): " + x);
var n:Int32 = 1;
var m:Int32 = n << 32;
trace("Int32(m): " + m);
```
If the static analyzer is on, the code ```var x:Int = 1<<32;``` will be optimized to 0 ( for javascript) and if off , to 1.
For Int32 it will return 0 ( for all targets) which is also wrong

Reproduce the linked try.haxe.org example with the static analyzer enabled and disabled, comparing left shifts for Int and Int32 on JavaScript and other targets. Trace how literal and variable shifts are handled in the compiler and verify that the resulting values are consistent and correct across analyzer modes and targets.

Written by the indexing model from the issue text.