[clang] [BoundsSafety] Allow 'counted_by' attribute on pointers in structs in C (PR #90786)

[Bill Wendling via cfe-commits]

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@@ -335,6 +336,22 @@ Attribute Changes in Clang
 - Clang now warns that the ``exclude_from_explicit_instantiation`` attribute
   is ignored when applied to a local class or a member thereof.
 
+- The ``counted_by`` attribute can now be late parsed in C when
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bwendling wrote:

You should mention that `counted_by` was extended to work with pointers in structs first. Otherwise, "last parsing" of the attribute doesn't make a lot of sense since a flexible array member is at the end of a struct.

https://github.com/llvm/llvm-project/pull/90786