clang-format: Fix bug in escaped newline calculation.

This prevents clang-format from inadvertently joining stuff into macro
definitions as reported in llvm.org/PR23466.

llvm-svn: 236944
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 9d29a26..6569bad 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -2987,6 +2987,8 @@
   EXPECT_EQ(
       "#define A \\\n  int i;  \\\n  int j;",
       format("#define A \\\nint i;\\\n  int j;", getLLVMStyleWithColumns(11)));
+  EXPECT_EQ(
+      "#define A\n\nint i;", format("#define A \\\n\n int i;"));
   EXPECT_EQ("template <class T> f();", format("\\\ntemplate <class T> f();"));
   EXPECT_EQ("/* \\  \\  \\\n*/", format("\\\n/* \\  \\  \\\n*/"));
   EXPECT_EQ("<a\n\\\\\n>", format("<a\n\\\\\n>"));