[TextAPI] Make sortTargetValues strict weak ordering compliant

Second sorting was not following strict weak ordering as it
does not follow transitivity of equivalence property.

If you build llvm with libcxx at head as a standard library with -D_LIBCPP_DEBUG_STRICT_WEAK_ORDERING_CHECK and -D_LIBCPP_ENABLE_DEBUG_MODE, then tests like llvm/test/tools/llvm-readtapi/compare-right-single-inline.test.test will fail

I don't have commit rights. Danila Kutenin [email protected]

Reviewed By: cishida

Differential Revision: https://reviews.llvm.org/D157958

Author: Danila Kutenin

llvm/tools/llvm-readtapi/DiffEngine.cpp

@@ -447,11 +447,11 @@ T *castValues(const std::unique_ptr<AttributeDiff> &RawAttr) {
 
 template <typename T> void sortTargetValues(std::vector<T> &TargValues) {
   llvm::stable_sort(TargValues, [](const auto &ValA, const auto &ValB) {
+    if (ValA.getOrder() == ValB.getOrder()) {
+      return ValA.getVal() < ValB.getVal();
+    }
     return ValA.getOrder() < ValB.getOrder();
   });
-  llvm::stable_sort(TargValues, [](const auto &ValA, const auto &ValB) {
-    return ValA.getOrder() == ValB.getOrder() && ValA.getVal() < ValB.getVal();
-  });
 }
 
 template <typename T>