[Issue 23011] importC: asm label to set symbol name doesn't work with externs

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23011

--- Comment #1 from duser at neet.fi ---
Created attachment 1845
  --> https://issues.dlang.org/attachment.cgi?id=1845&action=edit
fix

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