[llvm] [clang] [llvm][DebugInfo] DWARFv5: static data members declarations are DW_TAG_variable (PR #72234)

[Arthur Eubanks via cfe-commits]

aeubanks wrote:

we're seeing debug info verifier issues in Rust with this change, e.g.
```
 invalid tag
 !50 = !DIDerivedType(tag: DW_TAG_imported_declaration, name: "DISCR_EXACT", scope: !37, file: !2, baseType: !51, flags: DIFlagStaticMember, extraData: i64 0)
 invalid tag
 !61 = !DIDerivedType(tag: DW_TAG_imported_declaration, name: "DISCR_EXACT", scope: !54, file: !2, baseType: !51, flags: DIFlagStaticMember, extraData: i64 1)
 invalid tag
 !86 = !DIDerivedType(tag: DW_TAG_shared_type, name: "DISCR_EXACT", scope: !79, file: !2, baseType: !87, flags: DIFlagStaticMember, extraData: i64 0)
 invalid tag
 !97 = !DIDerivedType(tag: DW_TAG_shared_type, name: "DISCR_EXACT", scope: !90, file: !2, baseType: !87, flags: DIFlagStaticMember, extraData: i64 1)
```

is this expected?

(https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket/8764364541415601649/+/u/package_rust/stdout?format=raw)


https://github.com/llvm/llvm-project/pull/72234