Improve formatting of stream operators.

If there are string literals on either side of a '<<', chances are
high that they represent logically separate concepts. Otherwise,
the author could just have just a single literal (possible split
over multiple lines).

So, we can now nicely format things like:
cout << "somepacket = {\n"
     << "  val a = " << ValueA << "\n"
     << "  val b = " << ValueB << "\n"
     << "}";

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174310 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 0cfd990..34bccb9 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -669,6 +669,10 @@
              (Current.is(tok::string_literal) &&
               Current.Parent->is(tok::string_literal))) {
     Current.MustBreakBefore = true;
+  } else if (Current.is(tok::lessless) && !Current.Children.empty() &&
+             Current.Parent->is(tok::string_literal) &&
+             Current.Children[0].is(tok::string_literal)) {
+    Current.MustBreakBefore = true;
   } else {
     Current.MustBreakBefore = false;
   }