[clang] Use existing AvailabilityKind enum for code completion availability (PR #160296)

[Vlad Serebrennikov via cfe-commits]

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@@ -3039,6 +3039,16 @@ class _CXUnsavedFile(Structure):
 }
 
 
+# Converting the new enum names (full upper-case, underscore separated)
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Endilll wrote:

I think it would do better as a docstring within the body of the function

https://github.com/llvm/llvm-project/pull/160296