v: fix redundant emission of left expression in in infix expressions

[HectorPeeters]

This PR fixes the issue addressed in #22758. It prevents the left expression of an in infix expression from being emitted multiple times. This occurs in the following code example:

x() in [12, 13]

This gets optimized into:

x() == 12 || x() == 13

In this case this optimization is incorrect.

The fix I implemented checks if the left expression is an ast.Ident. However, I'm unsure if there is side effect information present in the compiler. Having this information available would allow this optimization to be applied in more situations.

_{Huly®: V_0.6-21210}

[spytheman]

However, I'm unsure if there is side effect information present in the compiler.

There is not yet afaik.

[spytheman]

Excellent work.

[medvednikov]

This kills the allocation optimization though and now x() in [12, 13] will result in an allocation for [12, 13]?