[llvm-cov] Use a stable sort on sub-views

We need to use a stable sort on instantiation and expansion sub-views to
produce consistent output. Fortunately, we've gotten lucky and the tests
have checks for the stable order.

This is needed to unblock D39245. Once that lands, we'll have better
test coverage for sort non-determinism.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316490 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-cov/SourceCoverageView.cpp

@@ -178,8 +178,8 @@ void SourceCoverageView::print(raw_ostream &OS, bool WholeFile,
 
   // We need the expansions and instantiations sorted so we can go through them
   // while we iterate lines.
-  std::sort(ExpansionSubViews.begin(), ExpansionSubViews.end());
-  std::sort(InstantiationSubViews.begin(), InstantiationSubViews.end());
+  std::stable_sort(ExpansionSubViews.begin(), ExpansionSubViews.end());
+  std::stable_sort(InstantiationSubViews.begin(), InstantiationSubViews.end());
   auto NextESV = ExpansionSubViews.begin();
   auto EndESV = ExpansionSubViews.end();
   auto NextISV = InstantiationSubViews.begin();