cgen: regression for Option return of C alias

[ttytm]

Describe the bug

After #21054 there is a builder error when returning an option that is an alias of a C struct that is not a pointer. It still works with a Result or regular-alias return type.

Workflow that run into it: https://github.com/ttytm/dialog/actions/runs/9044737428

Reproduction Steps

Unfortunately, extracting a self contained example is currently not possible.

For now, I would link a lib that runs into this regression https://github.com/ttytm/dialog
There, build the minimal example (for a repro only the color picker suffices).

Expected Behavior

Works as before.

Current Behavior

gcc

builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .
/tmp/v_1001/minimal.01HXM8YGFNVQ4870R5JFQ311AF.tmp.c: In function ‘indent__option_dialog__Color_str’:
/tmp/v_1001/minimal.01HXM8YGFNVQ4870R5JFQ311AF.tmp.c:3250:48: error: incompatible type for argument 1 of ‘indent_dialog__Color_str’
 3250 |                 res = indent_dialog__Color_str(*(dialog__Color*)it.data, indent_count);
      |                                                ^~~~~~~~~~~~~~~~~~~~~~~~
      |                                                |
      |                                                dialog__Color {aka osdialog_color}
/tmp/v_1001/minimal.01HXM8YGFNVQ4870R5JFQ311AF.tmp.c:284[9](https://github.com/ttytm/dialog/actions/runs/9045105152/job/24854491986#step:5:10):55: note: expected ‘dialog__Color *’ {aka ‘osdialog_color *’} but argument is of type ‘dialog__Color’ {aka ‘osdialog_color’}
 2849 | static string indent_dialog__Color_str(dialog__Color* it, int indent_count); // auto
      |                                        ~~~~~~~~~~~~~~~^~

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.5 35f6523

Environment details (OS name and version, etc.)

all

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