[APINotes] Make an assert in a std::sort call tolerate self-comparisons

libc++ debug mode verifies that a comparator passed to std::sort defines
a strict weak order by calling it with the same element.

See also:

- RFC that introduced the feature:
  https://discourse.llvm.org/t/rfc-strict-weak-ordering-checks-in-the-debug-libc/70217

- `strict_weak_ordering_check.h` in libc++ sources.

Author: gribozavr

clang/lib/APINotes/APINotesWriter.cpp

@@ -441,7 +441,7 @@ void emitVersionedInfo(
   std::sort(VI.begin(), VI.end(),
             [](const std::pair<VersionTuple, T> &LHS,
                const std::pair<VersionTuple, T> &RHS) -> bool {
-              assert(LHS.first != RHS.first &&
+              assert((&LHS == &RHS || LHS.first != RHS.first) &&
                      "two entries for the same version");
               return LHS.first < RHS.first;
             });