Fix a bug in the line merging.

If the first line of a merge would exactly fit into the column limit,
an unsigned overflow made us not break.

llvm-svn: 172426
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index daebc4d..8e55ddb 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -138,6 +138,8 @@
                "  f();");
   verifyFormat("if (a) return;", getLLVMStyleWithColumns(14));
   verifyFormat("if (a)\n  return;", getLLVMStyleWithColumns(13));
+  verifyFormat("if (aaaaaaaaa)\n"
+               "  return;", getLLVMStyleWithColumns(14));
 }
 
 TEST_F(FormatTest, ParseIfElse) {