clang-format: fix for \r\r\n produced in multiline block comments

Patch by Christopher Olsen. Thank you!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193678 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 991763c..2f6e06f 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -6984,6 +6984,17 @@
                    "  b; \\\r\n"
                    "  c; d; \r\n",
                    getGoogleStyle()));
+
+  EXPECT_EQ("/*\r\n"
+            "multi line block comments\r\n"
+            "should not introduce\r\n"
+            "an extra carriage return\r\n"
+            "*/\r\n",
+            format("/*\r\n"
+                   "multi line block comments\r\n"
+                   "should not introduce\r\n"
+                   "an extra carriage return\r\n"
+                   "*/\r\n"));
 }
 
 TEST_F(FormatTest, MunchSemicolonAfterBlocks) {