fix Issue 12719 - struct.c:705: virtual void StructDeclaration::semantic(Scope*): Assertion `parent && parent == sc->parent' failed.

Set `semanticRun` to `PASSsemanticdone;` immediately after the struct size determined.
Merge pull request #3537 from 9rnsr/fix12719

[REG2.066a] Issue 12719 - struct.c:705: virtual void StructDeclaration::semantic(Scope*): Assertion `parent && parent == sc->parent' failed.