[llvm] [llvm-ar][Object] Use K_GNU instead of K_COFF for archives with no symtab. (PR #82898)

[James Henderson via llvm-commits]

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@@ -14,6 +14,12 @@ RUN: yaml2obj elf.yaml -o coff-symtab.o
 RUN: llvm-ar crs --format coff out3.a coff-symtab.o
 RUN: llvm-nm --print-armap out3.a | FileCheck %s
 
+Create an empty archive with no symbol map, add a COFF file to it.
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jh7370 wrote:

It would be useful to know what is expected here, e.g. something like "Show that the output archive is a COFF archive."

https://github.com/llvm/llvm-project/pull/82898