[llvm-cov] Make an API more consistent, NFC

Make renderExpansionView() look a bit more like renderLine(), and
clarify its doxygen comment.

llvm-svn: 273773
diff --git a/llvm/tools/llvm-cov/SourceCoverageViewText.h b/llvm/tools/llvm-cov/SourceCoverageViewText.h
index 6753a59..36b7c96 100644
--- a/llvm/tools/llvm-cov/SourceCoverageViewText.h
+++ b/llvm/tools/llvm-cov/SourceCoverageViewText.h
@@ -33,9 +33,9 @@
 
   unsigned renderExpansionView(raw_ostream &OS, ExpansionView &ESV,
                                Optional<LineRef> FirstLine,
-                               unsigned ExpansionCol,
                                const coverage::CoverageSegment *WrappedSegment,
-                               CoverageSegmentArray LineSegments,
+                               CoverageSegmentArray Segments,
+                               unsigned ExpansionCol,
                                unsigned ViewDepth) override;
 
   void renderInstantiationView(raw_ostream &OS, InstantiationView &ISV,