[Issue 20163] New: Deprecated import in string mixin does not output diagnostic message

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20163

          Issue ID: 20163
           Summary: Deprecated import in string mixin does not output
                    diagnostic message
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: pro.mathias.lang at gmail.com

```
--- mod1.d
module mod1;
mixin("import mod2;");
void main() {}
--- mod2.d
deprecated module mod2;
```


This does not output a message, while the non-string-mixin version correctly
does.

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